The baby boomers who think they can live off Social Security are going to have a rude awakening. They’ll end up moving back in with their millennial kids and there will be a plethora of multigenerational households just like there used to be. Only it used to be that the most generations in one household was three. Now with people commonly living into their 90’s there could be four or five. Gonna need a bigger house.
From what I see, it's the other way around. Millennials can't afford housing, and are moving in (or staying in) their baby boomer parent's homes. Of the baby boomers who have no homes, neither do their millennial children - they all rent. So it's more of a sharing of rent arrangement for those baby boomers who don't own homes, sharing rent between multiple generations.
You can live off Social Security if your home is paid off, you have no debts, and your property taxes are reasonable. It's a tight squeeze but doable. If inflation continues to outpace SS COLAs as has been happening, then the squeeze will be a stranglehold. I don't rely on my SS income in retirement because I have investment income - never have counted on SS being there for me.