I think DM/M is pretty safe for now, unless the purported new movie comes up with a wild new round-heeled pairing. The thing is, in the early days of Highlander fandom, it was somewhat daring and dangerous to pair Methos and Duncan. Now it's so common they are almost like an old married couple *g*. The sheer wealth of DM/M stories makes it hard to break new ground. I kind of like a change of pairing and pace now and again. As a Dawson partisan, I just get excited when my favorite character gets any action at all *g*.
There's still a lot of stories to tell from all angles.