Level Cap Increase

[StouterTaru]

I did, and I doubt that would be the case if you blitzed the content. Remember that trials give diddily squat for EXP, and there are only 2 dungeons that are part of the MSQ (Snowcloak and Keeper of the Lake). From 49-50, you needed about 4-5 dungeon runs of AV, full clears with EXP bonuses, to get to 50.
So yeah if you finish all the MSQs and don't dawdle around with other content, you'll get MAYBE level 51 or 52, which is fine and just gives you a little bonus leg up on the expansion content to counter the fact that the people who finished it are decked out in gear that likely won't be replaced until 60 dungeon/raid content.

There were no level 50 dungeons in MSQ for 2.1, 2.2, or 2.3. 2.4 had a dungeon and a trial, 2.5 had a dungeon and two trials. I think it's safe to assume we'll have at least 1 dungeon in the 3.0 MSQ, probably a few.