It boils down to how much additional state you want to maintain in or to support multipath. The 32 bit constraint allows for a very simple implementation. I don't think applications are going to hit it in practice. Supposing one connection migration per second, the limit is not hit for one hundred years.
Counting on fingers … hmm well yeah 136 to be exact. And for space travel you can’t even migrate that fast, but then 100 years might mean something else. I still don’t like modifying the underlying semantics and I’m also a bit concerned about the path sync issue, especially on forward stations / offloads.
