How many of them are active? From my initial and non-exhaustive search, I see in the apple watch forum 7 threads being what I would define active, i.e., month
Using the same time frame, i.e., July and August, in the iOS9 forum there are over 500 (11 pages of threads before you hit the month of June).
Also for total volume, the iOS9 forum has 985 threads, that's basically an order of magnitude difference.
To summarize my opinion, I see only a handful of active threads and I don't see the volume being at a level where it could justify its own forum - just my $.02.