Haha. MCU has free reign to do whateverTF they want in Phase 2. They are in uncharted territory with a full tank of gas. It will likely be totally unpredictable so our predictions are moot.
I could see them throwing in E&E at the end of T:TDW. And after they are "defeated" along with the rest of the MoE, maybe they come back with a vengeance and unleash surtur in Thor 3.
maybe not. but any and all of this stuff would be cool to see on screen so Im stretching my imagination.