No More Classes?

[ChameleonMS]

So what happens if you happen to be a Lv 28 MRD then pass lv 30? Do you just become a War? Would you be able to stay a Lv 33 MRD?

You do not become a warrior until you complete the quest Pride and Duty. Additionally, you must level a Gladiator to level 15 to unlock this quest.
They are rare but I have seen a level 50 Marauder.