Combining households seems like a far-fetched idea to me.  Yet, I combined houses with my mother-in-law 14 years ago yesterday.  Long story short, we needed her and she needed us.  There have been regrets for sure (lack of privacy, she always takes my husband's side in arguments, etc.), but overall we've managed to get by.

Today I'm listing a home for a friend of mine whose mother-in-law is also moving in with them.  They're selling a lot of furniture and other belongings, although I've encouraged them to try to afford a place to store the items instead.

They're combining because of this extraordinarily difficult economy.  They are job poor - that is the work they do find doesn't pay enough to maintain two households.  This combination is the best solution for them to keep a roof over everyone's head.

I think we'll be seeing a lot more of it in the months and years to come.