For me this approach is working great. Like most good things, germination takes time. The best parts of HTM are still coming and the people interested enough to stick around will be there to witness their birth. Part of the beauty is that it really could be anyone who finds the next cool thing. This topic is more complicated than other hobbies, so it might have more turnover, but the rewards will be commensurate with the difficulty.
Personally, I believe that Numenta is the group who has it right. Other places will get there, but Numenta will get there first. The right minds are going to be drawn to the openness and accuracy here. There's no way to participate in the theory or application at most other projects of this type without being hired and then hidden behind secrecy agreements.
There are always theoretical better alternatives to everything, but in reality this is the place that fits my processing best and I don't even see a close alternative. Like any passion, this project isn't going to be fed externally. You have to decide to love it yourself. The community here gives me a path for problem solving while learning. It also challenges me, personally, because I know the absolute most about the neocortex among my friends, and then I show up at Numenta discussions and I'm never the one with the insightful comment.
If someone is really waiting for the biggest group to form, show up right after the big discovery that's coming eventually. There'll be a day when everyone was suddenly "always" a fan. It's okay to keep checking in and showing support with YouTube views until then.
Personally, I think the balance is being struck well between being open enough to feed the independent researchers, while being low burden enough that Numenta isn't shutting it down because of the resource drain. I'm grateful for what exists and I'm trying to build a meaningful contribution. I'm grateful that when my project is done that there's already an obvious place set up to share it, and an already-established community with enough background to understand why it's great. It's okay if the community ebbs and flows right now, as long as it stays alive through the lean times and stays focused through the rich times.