All they really need to do is show us a Constitution class we never saw before.
Then it could be a refit of a type we also never saw (eg: TMP Enterprise).
We've seen the Enterprise, Constellation, Defiant, Lexington, Excalibur, Hood and Potemkin. That leaves 5 or 6 other Connies we could see.
This of course assumes they care about what the 1960's Enterprise looked like at all. If the Klingons and their ships are any indication, they do not.
Then it could be a refit of a type we also never saw (eg: TMP Enterprise).
We've seen the Enterprise, Constellation, Defiant, Lexington, Excalibur, Hood and Potemkin. That leaves 5 or 6 other Connies we could see.
This of course assumes they care about what the 1960's Enterprise looked like at all. If the Klingons and their ships are any indication, they do not.