Some kind of residency would actually make the most sense to me.
I don't think Jon's voice will improve in any way. But having a residency would at least take away a lot of other stress. No traveling, family can be around, some kind of settled life, reduced crew, no need to play 5 shows a week. I mean, Billy Joel plays once a month at the MSG in New York. For 10 years now.
Doing something similiar - no matter in which extent - would make a lot of sense in my book.