They wouldn't identify as trans, but that trans would still be their medical status. They transitioned from one thing to another.

Diabetes or cancer isn't an identity, nor is gender dysphoria. It just happens that our gender is a large part of our identity, but gender dysphoria/being trans isn't specifically our identity/how we identify. We identify as the gender we transition to, not as trans or some half gender.

Some trans people DO identity as trans though and that's fine. Some others don't and see it as just a part of them and their medical history.

Your story of gender dysphoria being cured by science is basically what we already do now. We transition with the help of medical science, to be our true inner selves and that's been the only proven thing to help someone with gender dysphoria for the majority of the trans population. Describing in the story that people can change their genetics etc. to transition to reflect their inner selves, is still transitioning, but again trans isn't an identity. Their goal gender to present as, is their identity.