A few things:
- 3D does NOT require "a lot" more bandwidth. It requires, at most, a 50% increase since, with digital compression, redundant information between the two views can be eliminated.
- In the case of a network like ESPN, they use 720p at 60fps, which means it can still be 720p, but at 30fps per eye.
- At least in the beginning, sporting events will be covered in the same way earlier HD events were covered: with separate cameras, trucks and crews. The reason? Not every camera angle lends itself to 3D, and not every 3D angle makes good 2D. So, you run two operations side by side until 3D is more popular and they can start mixing the two a bit more.