My wife and I will happily celebrate our 20th wedding anniversary this August. We have three boys and she’s been a SAHM by choice for 13 years now. Before that, she worked as an educational-publishing editor, and still does a little freelance work here and there. We have no backup plan, as such, and I cannot remotely imagine needing one.
If I were to die, she would get a big insurance payout, and my family and hers would also help support her and the boys, I’m sure.
If we were to divorce, which is extremely unlikely, she’d get generous child support. (I used to work as a child-support prosecutor and know how that works, but even if a court didn’t order me to pay it, I would - they’re my boys, too, after all). She could also return to editing in jig time, too, since she has lots of contacts in the trade and many who’d be glad to hire her.