This comes with a caveat; we’re still a way out from launch. Because we’re heads down in development, we’re not launching a dedicated forum for Diablo IV yet.
However, we still want you to feel welcome to discuss the game amongst yourselves. While we may not be able to answer all your burning questions, we are committed to sharing updates with the community and participating when we can.
Taken from:
As I said before, a subsection could work, however only if Blizzard themselves uses it. If they don’t, then most folks won’t either and would instead continue using the Diablo 3 forums.