* Indeed, if you look at the footage as shot, that could well have been the intent right up until post production. The crew's dialogue and reactions are just as consistent with seeing the Excelsior with the Ent's name painted on it as what we ended up with. All they needed to change was the model show. I'd be curious to know if that was indeed the case.
As cool as that would have been, I don't think that was the intent for the final scene. Scotty just called the Excelsior a "bucket of bolts." If the ship had been renamed the Enterprise, it still would have been a "bucket of bolts" to Scotty and the audience, albeit a bucket of bolts with a different name. I think by that point in the production, the "Excelsior is Kirk's next command" thing was dropped.
Of course, the Enterprise-A ended up as a bucket of bolts in STV. Ironyyyyyyy!