Aside from all those probs revolving around 2.x (e.g. keeping subscribers etc) I think the main problem is the balancing in 3.0.

Yoshida has said that iLevel 130 is pretty high at the start of 3.0 and for that reason he doesn't know whether he should remove the cap now. So the decision seems to hinge NOT so much on what's happening now. Rather, what will happen later in 3.0