When I re-glaze your bathtub, I won't promise you it will look 100% as good as new when I finish, but I will promise you it will look 95% as good as new. Now that pertains to 95% of the tubs that I re-glaze.
If properly taken care of, a re-glazed tub will last just as long as a new tubs, if it has been properly re-glazed and if the proper materials are used. I use synthetic porcelain to re-glaze cast iron and steel tubs and gel coat to re-glaze fiberglass bathtubs. Just like the original tubs.
I am a one man show and I have been doing this for 26 years, and have very little trouble with my bathtubs.