Or how about including an NPC to fill a missing role? NPC's in this game are pretty capable and the code that dictates their actions is great. No reason you cant have one of them fill in as a healer or a tank. There are ways to do away with the trifecta. There are a million of them. You just have to not be lazy and be willing to take even the tiniest risk on something new.
It's a good thing that you can do exactly that in this game, then.
You can bring along companions into flashpoints and have them tank or heal if you want. It'll definitely be harder, but it's not impossible to clear content this way.