How realistic is it to quit my job for an extended absence (5+ years) and later return to a programming/IT position?

Not very realistic. 5+ is a long time to be away from IT. I took a 2 year break from programming to explore new things. I got fed up with the chosen path and moved back into programming. I was shocked to find out how much had changed. It took a lot of effort to move back into SW. It's not impossible but after a break of 5 years it will take some effort.

Over the last years I slowly moved away from programming and about three years ago I moved out of it completely. I still do some programming for fun but not professionally. I haven't had any regrets (so far:)

There are other jobs too! Why not do something different? Burning out and dragging on doesn't sound like a good strategy. You could move into something else and do it part time.

It's all about priorities and being home with your kids sound pretty important. If you can afford to quit your job why not do it? Why not do it for a year and then evaluate your situation?

Regards

Harry