On the other hand we've seen a constitution class starship on Enterprise and it didn't look like JJ's Enterprise. This could be the Archer from ENT or a reboot Archer.
Too much interdimensional crap going on for that kind of thing to be meaningful. We saw one ship - not the Enterprise - pulled from a universe which we have reason to assume was the old TOS one (although there are minor visual differences).
The answer based solely upon the story logic we've been led to think is used in the movie would logically be that "Enterprise" would be unchanged in the JJverse. I think that's unlikely, though, in terms of visuals at least, and it may never come up at all.