Not really many are "analog" and we already have GTX model. Some primitives are just buffers, some - memories (block RAM), one PLL. I do not think it is a "rocket science" to create functional models without precise timing.

As for different architectures - sure these will not work, but we keep all the primitives in "wrapper" modules to simplify porting. With missing primitives it will be possible to run complete simulation, after that you can start replacing primitives to match different devices.