I wish threaded comments would nest more even though that only plays well with desktop usage. It was the nicest feature of reddit to follow threaded conversations with ease.
I think the biggest issue is going to be discoverability of the largest community for a specific interest. For example, if people are interested in Diablo IV they are going to want to swarm to the instance with the largest community. Making that easy to find will grow communities very quickly.
They can change systems but the story can't change much.
There is a vibrant modding scene on Nexus for the game on PC. Lots of interesting mods to change the play experience. I feel the game will forever be solid but also somewhat disappointing. It had the potential to be so much more and isn't at the level of The Witcher 3.