Have they said that (with the expansion) they're going to move the current main scenario stuff that occupies the level 50 space back so that we encounter all the story content back-to-back at earlier levels? 'Cause that's not only the easiest solution to this particular problem, but also the right thing to do for the flow of the game in general.
I mean, the dev team has made a -lot- of content now. For any players coming into the game fresh, there's absolutely no excuse for there to be any amount of grinding. Everybody should be occupied with a main scenario dungeon, a side-quest, or an extreme mode something-er-other at every point along the way.