"Nope ;)"
No, I verified after asking, it is in fact 65,535 as I suspected.
https://forum.unity.com/threads/65535-vertices-limit.294585/Either that or y'know, the people that develop Unity don't know what the limit is.
65535 is also logical, 65000 would be arbitrary.
Edited 2017-10-19 02:33:40