I honestly don't believe there's an organization that offers a better combination of development & opportunity going forward. Flat out, the Canucks have the best goalie development program & it's not even close: Cory Schneider & Roberto Luongo were all-stars this season, Eddie Lack went from an undrafted free agent to becoming a solid NHL goalie, and Jacob Markstrom went from going through waivers unclaimed (last year) to arguably becoming a starting goaltender.
Also, I don't see much upside in Thatcher returning to school for his senior year; so if he decides to play at BC again, I think he'll be traded at the draft & the Canucks move on/develop another goalie.
I get the appeal of choosing the team you want to play for, but the grass isn't always greener on the other side (eg. Justin Schultz would've been way better off w/ the Ducks than the Oilers; and I believe Jimmy Vesey made the wrong choice not to sign w/ the Predators as his rookie mistakes would've been insulated by one of the best defenses in the league).
College hockey players should consider that if a team's willing to invest in using a draft selection on you, then they must really believe in you as a future NHLer - they also have a vested interest in you making it that far; whereas other teams that could've drafted you/passed on you might just see you as a free asset that didn't cost them anything if you don't pan out.