Even is support role is a good idea, it wouldnt get rid of the trinity system, thing is, we dont really have buffer/debuffers. Protect and Stoneskin dont make a buffer class, Bio and Virus dont make a debuffer. I think a class specialized on support and debuffing skills can come and give us a fourth role, but will still be limited and be like that.

As much as i love build theory crafting and all, i preffer honest lack of variety over illusion of free will. Take GW2 for example, all classes can do "everything" and therefore there is no "roles" since everyone should be able to tank/deal damage/heal other or self... This failed misserably, with the evasion mechanics, most parties went full on max DPS and just outDPSed bosses everywhere since they also can heal and take a few shots, and the down mechanic even if is cool, can be abused to beyond limits doing this, making a group of glasscannons suddenly immortals.