Unless gerrymandering is ended, The Republicans will be shut out. The Democrat's supposed strength is mostly due to the redistricing plans that they passed in 1980, 1990, and 2000 (and which got progressively worse). Our Republican Governors vetoed the redistricting measure each time, but even then, the legislature overrode them. We need that Common Cause stuff here, but even then, the legislature would probably veto it. Massachusetts is in trouble.
Doesn't Massachusetts have referrendums?
Of course, MA is the original home of the gerrymander. I'm not sure, however, even if some of that was undone, how much gains could truly be made. I don't think it would even be possible to gerrymander one House seat at the federal level for the GOP. As for legislatively-speaking, I can't imagine the gains would be all that much beyond where they are now. The preeminent problem remains an institutional one within the party, and until that is solved absent of the gerrymandering, the gains will be fleeting, indeed.
In truth, the post-1990 Census map for MA was quite friendly to Republicans, which is why they were able to pick up 2 seats and could have picked up 2-4 others (the CD Meehan won in 1992 had actually voted for Bush in 1988). Weld threatened to veto the map if it didn't meet his specifications, and the RAT legislators were afraid that an impasse (I assume that the GOP had enough votes to stop an override in at least one house) would throw redistricting to the courts, who would likely draw a map that would fail to protect the 4 RAT members with seniority who lived within a few miles of each other (Moakley, Kennedy, Markey, and Frank). The prior year, Weld had similarly shown a partisan bent by scheduling the special election to replace Conte for after universities were on summer vacation in order to aid the GOP candidate, who happened to be a conservative who had lost to Weld in the primary (his last name was Pierce IIRC); the GOP candidate lost by only 53%-47% or so in a very liberal district. Now, we all know that Weld ended up being a worthless RINO who did not move a finger to build the state GOP, but it seems like he at least started off on the right foot before being led astray.