Adding new or interesting content will not work without a major change in the backbone of the game.

They can add 100 unique dungeons, 50 8 man instance boss fig...."Raids". 10,000 strong unique voice over quest in the expansion.

But if there is still 1 max level raid and dungeons are for nothing but token gear... the game has the same problem as it has now.

You need complexity in a mmo, you need grind in a mmo. The goal is to make them fun. Easy, Ultra balanced, simple = boring and extremely limited of a game. MMOs should start off ultra simple and get more and more complex and deep as you get to endgame. If a player cannot figure it out THEY DESERVE TO FAIL AT ENDGAME. the catering to the lowest common denominator is why game are getting more and more blah as time is going on. Complexity and depth + alittle bit of unballanced > ultra simplistic and perfect balance.