It will also be interesting to see how long they play on Morgana and Morgause not knowing that he is magic.

I'm sure Merlin will expose himself to them sooner or later for no other reason than he exposes a plan of theirs and has to stop them like any other baddie. However since it's Morgana and he's probably still smarting over what he had to do to her last time, he'll just defeat her and let her go... against her better judgement. Or something like that.

I'd like to see more scenes between Merlin and Morgause. She knows about Arthur's great destiny, so she must know about "Emrys"/Merlin's role in events.