I would be surprised at BOS-SNN/MAN from DL. They have just announced their long haul updates and MAN did not get anything yet.
There is really no hubbing carriers at BOS. DL/NW merger may make them biggest (not 100%), but it is certainly not a hub as we would call it.
I would think that up gauging aircraft into MAN maybe next, to pick up some PAX affected by BA/BMI, and hopefully a DTW-MAN leg.
Just my 2 cents from this side.