It's hard to say for sure, but at the moment it looks like ~10-15% of class-based locations will not re-open due to business failure? So that's not a dramatically reduced supply, and additionally a lot of these places weren't sold-out to begin with (except in say NYC or LA where popular classes have waitlists). I personally think the desire to be social + in/person will soon exceed people's concerns re: safety, especially in areas where the COVID rates are low.
> (b) class costs plummeting due to logistics and competition
I think this is unlikely at least until social distancing goes away. The average class size has decreased significantly in order to make social distancing possible.
Pre-covid, classes at our gym were sometimes so packed that you couldn't comfortably do a forward lunge without stepping on the person in front of you.
>The best hope is (a) social pressure to attend class //
By class I assume you mean some sort of organised fitness events? Do people do that for social reasons - I'd have thought the primary reason was not wanting to wobble like a jelly when you walk up the road; then perhaps longevity??