You have TT, and road bike, why not add mountain biking also.
Im a roadie only, and happy with whats available; but introducing mountain bikes with off road courses, would include the MTB community - something to think about.
Adding some off road courses to watopia; with tracks through bushland/scrub/rocks - jumps etc. ( only MTB avatars can access the offroad sections - much like the LVL11 access to alp/jungle )
Yes, it would mean new models, animations and map alterations, but potentially could grab the attention of an already cycling community into Zwift, and also add some fun stuff for those who just ride roads only.