King Daniel wrote:
Eh, if they could retcon the Enterprise NX-01 into the continuity, they could slip another one in afterwards. Harve Bennett's unmade prequel movie Star Trek: The Academy Years featured an older USS Enterprise.
It's always possible that a very prominent non-Starfleet ship had the Enterprise name during the era. That ringship from the TMP rec room wall, for example...
would seem to predate the NX-01 based on images seen in "First Flight".