I would welcome an expansion or two that doesn't increase the leveling cap. The MSQ would be rather short but could potentially have alot of story and lore to provide for those that like it (think of all the story we had in ShB but without having to do fetch quests to buffer your level). There would be far more dungeons right off the bat. Areas would all be challenging and relevant. Difficulty could pick up where the previous expansion left off instead of resetting and working its way back up.

Devs would need less time spent on leveling content. Balancing classes (it would have been done prior). And more time on dungeons, MSQ, and endgame. Everyone would also start at the same place in the 'endgame' so population disparity would be less.