[Chemahkuu]

In the first Romulan War book we see the NX-03 through NX-06 lost in short order. Challenger is taken over while standing still and self destructs, the ship never even fired a shot, she was the most useless of the lot.

Discovery is lost breaking up in the atmosphere of the planet its orbiting and Travis narrowly escapes dying on her.

Atlantis is severely damaged by a Bird of Prey she nearly rams, using her self destruct to take the BoP with her.

Endevour I can't remember what happens to her but her loss in implied more than described, but she is definitely lost.

Columbia is mentioned disappearing in the same star system she take damage in the Destiny trilogy tying into those novels.

The Enterprise spends the remainder of the war being the only NX ship and getting the living shit pounded out of her constantly for years, she undergoes a supposed massive refit in book two at Earth only to be battered saving Earth from a Romulan attack, and finally at the final battle of Cheron taking significant damage. Shes far too badly battered to remain in service at all and is ordered home to be scrapped at the battles end already.

As of August 2161 no NX ships are in service or space worthy, the Intrepid class Intrepid in the story is likely in as bad shape and scrapped too, with the NX-07 started and finished after the war altogether and possibly a warp 7 new generation NX inside.

So yup, Intrepid onwards marks a new life for the class, but the first 6, not so much.