What are the chances of his turning pro after his Junior season? If his team is viewed as not a contender next year there could be little motivation to stay at Orono.
And, if he plays his senior season, you run the risk of an August free agency if he feels his path is somehow blocked.
I'd imagine there are a few factors.
1. What are is educational aspirations. i.e. does he want to finish school
2a What's best for his development
2b. What role would he play in PRO next year
With how Boston uses their goaltenders, I don't think he'd be concerned with being blocked. He's actually in a great situation if you think about it. The team #1 is 32yr old w/ only a year left on his deal. Would Boston offer Rask a long-term deal? IDK, but it'll cost them to bring Rask back. In the system they have Vladar, Keyser and Lagace.
Lagace is a career journeyman and 27yr old, he's not a guy anyone expect to be a NHL goalie.
Vladar is 22yr old and having a monster year in PRO. Could he maybe slide up to #2 behind Rask next year? Could he take over the reigns if Tuukka walked after next year? Lots of questions there
Keyser has #1 upside, but the injuries are a concern. He's still only 20yr old and if Vladar goes up to BOS next year then Keyser most likely becomes the #1 in PRO.
Maybe Boston lets Lagace walk after this season, Vladar goes up to BOS to replace Halak (lots of risk there IMO) and they have Keyser/Swayman split time in PRO. They could also sign another goalie to tandem with Keyser and have Swayman go back to Maine where he gets every start and sees a ton of shots.