A third subclass, believe it or not, is going to be incredibly difficult to create. Many people believe the subclasses are seperated by Offensive and Defensive, leaving room for a Utility subclass. This is false and should not be practiced. The subclasses are in fact seperated by PvE and PvP compatibility. Yes, both are capable in both areas, but one will always do better in the other and we all know it. Knowing this, Bunjie doesn't have much left to branch off of. Would the third be an awkward mix of the two? Or would it lean to one way more than the other? It's hard since the only major events to consider is Nightfall and Raids for PvE.

As a Titan getting a ranged special fills a need, but is inconsistent with current player design. I'm thinking along the lines of a juggernaut or over shield subclass, perhaps similar to sun singer.