Everything I'd like to see CAN be implemented within D3. However, I'm not sure blizzard is willing to risk drastically changing D3, so a D4 announcement would be exciting because it means they would essentially have a clean slate to work with.
Maybe blizz could make a stand-alone expansion then make some drastical changes to d3 to that.
Going stand alone is the best way to make a new, hypothetic, expansion for D3. This way they can keep RoS like this and start anew without making a new game; classes, spells, graphic can be reused but with a different itemization, game system and not stacking insane damage multiplier for a new level cap.
New players can buy D3X2 without buying Vanilla and Ros, which is a nice saving while, hopefully, Diablo 3 will go into a more RPG direction like the predecessor and other games of the genre out there right now.
New players can buy D3X2 without buying Vanilla and Ros, which is a nice saving while, hopefully, Diablo 3 will go into a more RPG direction like the predecessor and other games of the genre out there right now.