Maybe you missed it in the OP but the idea was to replace 85 with a 76 command tank that gives offensive bonuses in the doctrine lineup. While 76 would not be a stock unit at all. A similar thing happens with Panzer IV.
76 is already complete shit, people use it because its their only option when they don't use cookie cutter doctrines. Those doctrines are not going to be useless just because they no longer house a staple call-in that should have been a stock unit in the first place.
i did miss that and i don't really have any thing to say to that because it's a huge change to make; i have no idea how it would play out.
useless, no, but it would weaken them significantly because you can no longer go t4 and produce 34/85s. i don't know how much of an issue that would be but it does effect any strats that do that.