It's too bad SNHU doesn't have a more prominent hockey program, or else they would be the perfect addition to complete a regular 4 team field, with the two high-profile teams coming into town from opposite ends of the state, and with St. A's and SNHU being a very short ride across town from the arena. But for that reason alone, I'd put them at least "on the radar" in this fictional futuristic tourney.
In the meantime, there are D-3 programs at Plymouth State and New England College (I believe the latter currently plays in the same conference as St. A's?) and maybe it would be fun to rotate them and SNHU every 3rd year until one emerges as the best 4th partner?
If nothing else, it might breathe some life into an otherwise dying event (Riverstone), energize some emerging programs and give them a nice moment in the spotlight, and bring a lot of students into downtown ManchVegas for a night or two of fun and games.
Long-term, either it becomes the formality of The Beanpot (basically BU vs. BC, or in this case UNH vs. Dartmouth) ... or one or more of these other emerging programs breaks through to establish tnemselves at the D-1 level.
Sound far-fetched? Not really ... and while St. A's undergrad enrollment is slightly smaller than Merrimack's, SNHU's enrollment is more than that of both Merrimack and St. A's combined. Nothing that will happen overnight, but for a visionary, this could be pretty exciting stuff to really energize the alumni. I hope to live long enough to see something like this happen, I really do.