Well, they've finally gone and done it. With only a month to go before they launch their (doomed) Vessel Of Hatred expansion pack, the Diablo IV dev team have announced their own 2.0 reboot... just like Diablo III did.
From Kotaku:
Diablo 4's next big update arrives in October as part of the game’s next season, which is also coming at the same time as its first paid expansion. This new update, which is going to be tested by players in September, is changing quite a lot of things, including the level cap, how monsters scale, the paragon system, and much more.
There's a PTR, of course, since D4's devs have no feel for their own game and need players to tell them if it's good, and the changes basically adjust everything about the existing game... slightly.