While I get along fine with my mother-in-law, she drives my husband bat-guano crazy in about three minutes. She's also getting up in years and no doubt one day will require in-home care - we already see signs that her short-term memory is degrading. She has expressed her wishes to live with her daughter since she doesn't want to be eaten by a snake.
We will of course visit often and help as much as we can when the time comes since SIL doesn't live far away from us... but we also breathed a huge sigh of relief that MIL will not be living with us.