Do you think new websites like this are ever going to break people's reliance on the big players like FB/Twitter or are they always destined for smaller and niche communities?
Unless the public becomes interested in text-based content again, I don't believe that communities like this will ever become hugely popular. One could hope that it would be popular among the people that DO like text-only discussions and long-form, though.
Except you can't really do long form on here
For some people just reading these reply threads is long-form. I'm not saying you're wrong--however, it may be quite a shock for some people who are used to Facebook to come to a place like this where there isn't any content curated for attention grabbing or instant virtue signaling (beyond our word choices, of course).