Here is one article that explains the phenomenon.
It should be noted that "in the good ole days" it appears that caring for the elder for extended numbers of years was pretty much not a consideration. Now it is.
The sandwich generation isn't really a single generation. While it comprises the end of the Baby Boomers, those that were born late enough to still be middle aged and in the workforce, it also comprises those of us that are Gen X'ers. So dh is the very last year of the Boomers, but I am four years into the X's and we have this shared responsibility.
By comparison, my mom and his mom both had extremely limited years of elder care giving. The Greatest Generation - their parents and even themselves as people tended to have children much younger - came through the Depression while still young, lived through the prosperity of the 50's and 60's, had company pensions, didn't have to move a lot in order to keep their jobs. They could stay in one place, get a mortgage young, pay the thing off many years before retirement, and generally did okay for themselves. My grandfather and many like him lived in the era in which one did not have to have two years of professional training, keep expensive professional licenses, or get a four year degree in order to get decent employment. On a high school diploma only, and for many an 8th grade education, they could get good work, stay at one firm, and end up with a pension and retirement benefits never having to go far from home to get it. It wasn't obviously all a bed of roses, life never is. Just statistically speaking they had some economic things going for them and for the early Boomers, that the late Boomers and the Gen X'ers do not have. They also had their heaviest use of the medical system at a time when it was a lot more reasonably priced as a percentage of income, and Medicare didn't restrict very much. That has not been the case for the later Boomers and of course my generation is feeling the squeeze big time on health care issues. Medical bankruptcy was not a thing then, but it is a very big thing now.
Millenials need to go to school a lot longer in order to be gainfully employed, start at lower wages in reference to COL and inflation, and will have to move A LOT - as started becoming more common with Gen Ex - to remain employed. Now suddenly people often do not live near their elders. But the older Boomers remembered with love and longing that grandma and grandpa lived next door, and mom and dad took care of them. They didn't have to move. They didn't have to change their lifestyle. That was also a generation with no expectation of "handicap accessibility" and such, things that many Boomers now expect shall be provided no matter what the cost, no matter whether or not they have the money to provide it. So the early and middle Boomers who still got to retire at 62 seem to think that nothing should change, and they should be able to age in place, in the manner that they demand, and everything should just some how fall into place. They do not understand the pressures their kids' face, the economic reality for their children and grandchildren, and the crushing medical bills that everyone NOT on Medicare tend to face with these high deductibles and all kinds of things being disallowed, nor do they understand the issue of student loan debt as tuition/room/board outpace wages by 415% in the last decade. It is beyond the scope of their experience, and as is typical of human nature, they aren't super inclined to figure out "how everyone else lives". Some will do so. Some will wake up and go, "Wow. How can I make this better for my kids? Maybe I do need to move to be closer, maybe I do need to stop taking expensive vacations every year, and save a little of that to put a wheelchair ramp on the house, maybe I should make some end of life directives and get those things in place, maybe I should sell my house and use the equity to help the kids make their house handicap accessible or pay for some in home help or...." some will definitely do that because not all humans, by any stretch, are adverse to change of perspective. Unfortunately, a lot of people will end up being in the "my way or the highway" camp and kill their kids health when they could make it a little bit better. Stubborn is a pretty strong character trait in a lot of retired people.
As Heigh Ho indicated, regardless of what they want, unless they are determined to die in their homes, laying on the floor for hours or even days in agony, despite their protests and the mounting pressures on their kids who are still raising families and need to work to 65-72 years of age in order to even think about getting out of the rat race, they will push the envelope until it can't be pushed further, acquiesce to moving in with one of their kids, and then likely proceed to be very angry, sullen, my life didn't turn out the way I wanted it to NON willing participants in the adult child's household. That has been my experience. Except for in cases of abuse or abandonment, my generation is reluctantly working ourselves into early graves to care for uncooperative elders. They don't mean to be bad, or nasty, or selfish jerks. They don't see themselves this way. They see themselves as victims who have been forced to live in a manner they never wanted to live. Among our family, extended relatives, friends, colleagues, and acquaintances, my own paternal grandmother has been the ONLY easy going elder for family to care for. She was a delight and brought great joy to her kids, grandkids, and great grandkids as she became increasingly more dependent. We only used assisted living for the very last year because mom and auntie were having their own health problems, and we grand kids were raising young children of our own and couldn't physically care for them and for her.
The other scenario is the juggling act of moving out of your own home and moving in with the refusing-to-give-up elder, abandoning his or her own family in the process until such time as A. assisted living opens up assuming there are assets to pay for it or B. require round the clock supervision and physical care and go to a nursing home.
These are the two things I see a lot. Not a whole generation of ungrateful children being jerks to their parents. However, as a result of the pressure, I predict that my generation will be less healthy in middle age than the previous one, and may in fact not live as long. Stress takes a toll. Financial pressure for the well being of three generations at once is crushing. I do see a LOT of families in which the Boomer parents were pretty dysfunctional, and oft times downright abusive, so there are a LOT of us who really recoil in horror at bringing such people into our homes because they will be such a profoundly negative influence, namely my father figure who became violent. With the exception of extremes, regardless of what people say, most end up killing themselves to figure something out, and do not just abandon old people willy nilly.
For what it is worth, all of you should familiarize yourselves with the Filial Laws in your states. 30 states have Filial laws. Most of those laws are rather old, and many times they are not enforced. They are kind of dusty laws that date back to the colonial era which took them from European laws that dated to the Renaissance in which states created laws making it mandatory for adult children to provide financially for their elderly next of kin - which given the death rate meant you might be the lone survivor in charge of grandparents, aunts, uncles, cousin, who knows - to combat poverty. These laws still survive, and again, while mostly "on the shelf" occasionally social workers and law enforcement do take them off the shelf, blow the dust off, and go after someone. In three states, Pennsylvania is one, I can't remember the others, there have been some attempts to bring back this enforcement. Pennsylvania changed its law to state that unless an adult child had been abandoned for ten years prior to reaching the age of majority, he/she was financially liable for the care of the parent. Abuse was not included. So if mom beat the crap out of you, or dad molested you, according to Pennsylvania law, you can be held responsible for caring for the abuser. It is hard to say if judges will be willing to enforce or not. I suspect that some politicians who want to cut nursing home coverage from Medicare just might.
I have been on the receiving end of a zealous DA, social workers who wanted him OUT of the psych ward and off the county dole for his care, and law enforcement that did not want to supervise him in a halfway house or he county lock up.
My case is extreme. But please, don't be naive. Times are a changing and there are going to be far fewer workers paying into the system for every elderly person that needs financial support and physical assistance. In the future it may no longer be legally acceptable to "do what you can" or "do your best" whatever that is for you. If politicians decide to save money by forcing a lot of elderly out of nursing care and requiring adult offspring to provide, x y z, you don't want to be unprepared.