The Wormhole wrote:
^^Although it does fit with Countdown to Darkness showing that there was indeed another Enterprise which really similar to the Constitution design likely before the 2233 timeline split.
April's Enterprise in that comic was a) built after Nero's incursion in the timeline, and b) looks almost exactly like the nuEnterprise, not the TOS one shown in the Enterprise history photos Decker shows Ilia. Even if we take the comic to be canonical, we still don't know if April's Enterprise exists in the prime timeline, or if it does, what it actually looked like.
And I also believe that the USS Constitution NCC-1700 isn't the prototype but a replacement of the prototype. I also believe that the Connies had enter into service a few years after the Federation was founded, between 2162 to 2170.
While I don't agree with your assessment at all (i.e. I believe there was no other Enterprise between the NX-01 and Kirk's TOS NCC-1701 regardless of what some tie-in comic shows or how one chooses to interpret Decker's use of words), I will state that there is also no canonical evidence that the U.S.S. Constitution's registry number is NCC-1700. Therefore the class could be older than previously known, as you infer, if registries are chronological. However, I seriously doubt that the class is as old as the founding of the Federation.