My personal family left over a period of 2 years. This occurred 5 plus years ago. My siblings with their families are all still ragingly "in" but since none of me or mine are actually DFd, they are somewhat fragmented in how they chose to deal with us and associate with us. Some more, some less.
I dont think they (my in family members) realize how very close to the edge as far as being mentally ready to walk some of the younger still in family members are. These young ones confide but vaguely. I listen with complete empathy and support but do no "campaigning" for leaving.
I think it should happen organically on its own if that is the choice.