It wouldn't be surprising if the
Daedalus far outlived the NX, considering that the latter was a testbed for a radically new propulsion technology. An audacious experiment is likely to fail, or to get outdated by a "production model", in a short period of time - whereas the
Daedalus class could have been an unremarkable development from the 2130s or 40s that featured no risky or experimental technologies. Also, nobody would be eager to develop a direct replacement to the
Daedalus now that the Warp Five Engine was the hottest news; Starfleet would first build successors to the experimental NX class and only then concern itself with finding a replacement to the lesser
Daedalus.
As far as the canon vs. novels debate is concerned... We don't canonically know what the
Daedalus class looks like. All indications are that it is unrelated to the sphere-cylinder-two-cigars tabletop model glimpsed on Sisko's table, because this model would not be well suited for housing the 228 crew that are canonically known to be aboard the sole canonically known
Daedalus vessel, the
Essex, at the time of her demise.
Canon is "leaky" in other ways, too. We don't really have to believe that Starfleet would never have given a "proper" name for the NX class. Instead, in all likelihood, that class was officially named the
Enterprise class, just like any other.
We only hear the expression "NX class" mentioned three times in aired Star Trek - in just two episodes.
1) In "Fortunate Son", Archer uses the expression "This is an NX class Starship" as a threat to his Nausicaan adversary. That is, "NX class ship" is a descriptive term, not a class name; it establishes the nature of military threat posed by Archer's ship. Similarly, a USN skipper might threaten his enemy by saying "This is an AEGIS class ship - so your puny fighters won't ever reach missile launch range. Wanna think again about that attack of yours?".
2) Later in the same episode, Mayweather says that "There are three more NX class ships on the drawing board". Again, it would be valid to argue that NX class is a descriptive term. Also, why do these ships remain on the drawing board? Is it because they have to be drawn? Makes little sense since the blueprints are already complete - unless they are of
different NX designs, being drawn to improve upon the
Enterprise class...
3) Finally, in "E2", T'Pol identifies the duplicate
Enterprise by saying "It's Starfleet, NX class". She does so before the ship is within visual range. Easy to argue, then, that she only identifies the general category (NX, easily discerned because the Warp Five engine has a distinct signature) rather than the exact class (
Enterprise, even though at that time there would be no other NX classes, and presumably no other vessels in this particular NX class, either).
Interpreting "NX class" as a descriptive term rather than a class name would also be consistent with how the USN does things. In USN practice, the combination of letters preceding the registry number describes the type of the vessel, not the class. A DDG class ship is a guided missile destroyer, even though the USN might have three different classes of DDGs in service simultaneously.
The letters "NX" actually make rather good sense in the USN scheme of things... N indicates nuclear propulsion, a propulsion type that sets all the N ships apart from others in terms of performance (mainly range/endurance). Starfleet could well use N to denote the exceptional propulsive system of the
Enterprise class, too! And X could stand for eXperimental - although considering the explicit nature of the
Enterprise class, it's more likely to stand for eXplorer.
As for the fact that nobody ever says "
Enterprise class" on screen, I wouldn't sweat that. Nobody ever identified the class of Kirk's TOS ship on screen, either, not during TOS.
Timo Saloniemi
