According to at least one source, Blizzard has at least one more expansion coming for the Diablo 3 game. There are has not been any support notes posted or even any speculation as to what gamers can expect with the expansion at this point. Fans have kept from demanding to know about it and that might say a lot for what the game is right now.
Could the game be that perfect that players are not worried about a brand new expansion? For the most part, as a gamer, you seek to have the game developer cater to you and when the gamers are not chatting about improvements, you might have the perfect game on hand.
That does not mean that Blizzard should not bring on an expansion, but it does mean that Blizzard should be careful not to wreck what it already has with an expansion that could be full of bugs and other gameplay issues.
I love WOW, I hit the level 100 in just 2 days with Duggi Warfounder addons.