I think a lot of it is that tons of priests would be outraged if the FSSP or another 'JPII' priestly order were allowed into Boston. So for all the talk of 'denying the faithful the Eucharist' it seems that not all possible remedies are 'open for discussion' - in fact, there's only one 'remedy' that seems to be 'open for discussion'. It's pretty hypocritical.
The competition from an Order, versus closing a parish, the money is on closing, because that would be cash in real estate strapped Boston, IMHO, but I am about a thousand miles from there.
If the FSSP would celebrate the Novus Ordo in addition to the Tridentine Mass, I'd bet O'Malley would not have a problem. The FSSP won't allow their priests to concelebrate with the bishop or other priests for fear of being "contaminated" by the Novus Ordo. I can see why a bishop wouldn't want this attitude in his diocese.
A parish with an indult Mass is not the same as an all Tridentine Rite parish. I wonder if there are enough traditional Catholics in Boston to support such a parish.