There is a guy in California - you can see his collection on Tank Fixers - who has no fewer than 20 operational or at the worst semi-operational MBTs spanning all eras including the 1970's/80's with a handful of T62s and '72s.
Additionally, he has a machine shop capable of completely rebuilding tanks if need be.
I
think the guy is far enough away from any metropolitan areas that in the event he'd be safe...and he'd become a huge asset for whomever could convince him (in whatever manner) to work for them - CivGov, MilGov, marauders, what have you.
Shit I could see in terms of sheer desperation stuff being pulled out of armor and military museums; a working Sherman is
still a tank, and when your opponent is a bunch of guys with hunting rifles crouched behind a log and dirt berm...well...advantage: tank owner.
