In 2286, the Excelsior is still in its test-run phase and there's no way they'd already have them in production without knowing if transwarp drive was practical.
It doesn't appear that "the Great Experiment" was in production, or about to replace anything much (although curiously enough, the "testbed" had apparently been built with full operational gear such as sensor and weapon emplacements). But we know of one new cruiser design from the 2280s already - the Constellation
. And we saw the Miranda
, which falls between the Constitutions
and early Constellations
in terms of registry numbers.
In contrast, we never saw or heard of a Constitution
that wouldn't have been a refit of a TOS era original.
It's not as if we're left grasping at straws for ships to fill the gap left by Kirk's hero ship class retiring: to the contrary, this is one of the eras where multiple options present themselves. And this is one of the eras where we get the sense of something ending, as the TOS design aesthetic disappears in a very sharp cut. Dramatically, Kirk bows out, and so does his ship - twice! It thus feels wrong on multiple levels to think that nothing changed in the story of the Constitution
class at large here.