In today's NE Alliance press release, B6 mentions that starting this fall, they'll be running a split operation at LGA between MAT and Terminal B, with all operations to be eventually consolidated at B. I'd imagine the full move will be dependent on when the new concourse is finally finished and all gates open. It'll be interesting to see what routes (i.e. the more leisure focused or the more business focused ones) they keep at MAT vs. Terminal B.