I'm taking this as those communities then forming one community that doesn't have to rely on a single instance's community to "survive".
Haven't put too much thought into this but I think that would at least lessen that problem, especially for new niche subjects popping up. The difficulty for existing niche communities starting anew here will probably remain but I'm hopeful for the future.
That does sound like a reason to be hopeful for the future. Thank you for telling me about this.