Theoretically, the version "number" in this case is technically not a number, because you wouldn't do any math operations with it, it's more like a string. So 3.1415926535897932384626433832795 and 3.14159265358979323846264338327950 are two different strings.
Practically, since TeX will have no new features as they only fix bugs now and the last bugfix release 3.14159265 was 7 years ago, I think we'll actually never get there.
