Tough one. I don't think there's any right or wrong answer, just what you and your husband are comfortable with. (Though you do have to be on the same page about it.) In some cultures it's expected that the adult children will take care of their parents in many ways. I don't think that expectation is very strong in mainstream US culture, however.
Personally, I would not like the expectation that I will take care of a competent adult, who got into a bad financial situation through their own poor choices--whether this person is my parent, my child, my SO, etc.. If it was through circumstances beyond their control, and we always had a good relationship, and they had done/did a lot for me in return (even if non-monetary), I would be much more open to working something out.