Wasn't a major part of the problem that the design kept changing based on the pushed timeline? So what we are getting now is completely different from what was

Wasn't a major part of the problem that the design kept changing based on the pushed timeline? So what we are getting now is completely different from what was planned in 1996 to be launched in 2007? If that's the case, and the JWST fails to deploy, we probably wouldn't just build another copy of it - we would build a completely new/reworked space telescope that would take another 25 years to design/launch.