I think there's a real justification for giving the 9 a dedicated bus lane and cutting back on the number of stops to make it more of a BRT service straight to Copley, similar to the CT routes. I'd advocate for a proper light rail branch, but I don't know where you'd make the connection from Broadway Station westward now that the South Bay Interchange is so massive. There's definitely the ridership to make that a viable and sustainable thing.
Alternatively, I'd also love to see a full Green Line branch that comes off just past Symphony and somehow gets down Melnea Cass, connecting to Southampton Street and ultimately Dorchester Street and E Broadway. Stops at Ruggles, Washington, Mass Ave, South Bay, Andrew, Old Colony, Perkins Sq., I St., L St. and Farragut (or some such). Sort of a first link in the Urban Ring. Might be more feasible as a Silver Line thing, I guess.
Alternatively, I'd also love to see a full Green Line branch that comes off just past Symphony and somehow gets down Melnea Cass, connecting to Southampton Street and ultimately Dorchester Street and E Broadway. Stops at Ruggles, Washington, Mass Ave, South Bay, Andrew, Old Colony, Perkins Sq., I St., L St. and Farragut (or some such). Sort of a first link in the Urban Ring. Might be more feasible as a Silver Line thing, I guess.