One thing about terminating the (A) at Oak Square: the car barn is long gone, replaced by the YMCA. So you can't really have tracks that just terminate there. It needs to go to Watertown Yard, where at least there's some storage space still, may as well run revenue service there.
Interesting, I did not know the YMCA was a rail house, or where it stands now anyhow. I was considering that it would perhaps be possible for an LRT to loop around the roundabout at Oak Sq? But I suppose there should be some way trains could terminate and be cleaned or whatever considering that this future GL would have more trains and more capacity given such things as better signaling as a top priority as well. But yea, I was figuring maybe something like Heath St. could be done at Oak Sq.
It would be pretty cool to see at-grade GL service down Brighton Ave thru Allston Village (replacing the 57) and have wicked fast service right thru BU with a Comm. Ave. Subway where the A and B would utilize. I imagine the B would pop out from underground after Harvard Ave westbound around where Griggs is now. There's no traffic intersections to contend with and Griggs PAX could walk the 300 ft. to Allston St. The B Line would become a rocket with this stuff done.