Animesuki used to be pretty popular for Higurashi and Umineko discussions, but it’s basically a ghost town now. There was, at one point, a fan forum called Hinamizawa, but it fell into disuse and I don’t believe it’s still up anymore. I’m sure that more fansites will spring up eventually, but there is no immediate successor to Rokkenjima, if that’s what you’re asking. I’m not sure there ever will be.
There is going to be a new Discord channel hosted by some of the members here, you can look into that.