Instead of one over the other, what might happen is the role of mo-cap actor and animator become a single role. Animators and actors both create expressions and poses of the character. Animators already film themselves in poses for inspiration.

In the future, a single person might end up taking their own mo-cap video as well as polishing up the animations for several characters.

Reminds me of how people just shoot their own podcasts now. It's just become that easy. At some point you might add to the team, but if you want to just try it, you can.

Animators are still needed, because not all motions can be captured.