This is obviously devastating news for Brown. You can find a direct link to the Providence Journal's article here.
I agree with @EdwardLeeSun. While this will impact the Bears, it should be noted that Brown is still a very lethal team( you can find a link to team stats here). Dylan is an integral part of the offense, but the Bears still have Kylor Bellistri and Henry Blynn, who dropped 58 and 48 goals this year, respectively. The loss of the Tewaaraton Award Finalist is a hit, but the Bears have a lineup full of hitters. They didn't drop 16+ goals/game this year just because of one player.
One bit of good news is that it still unknown if Dylan is out for the entire tournament. If Brown can beat Navy, there might be a chance the kid is well enough to play. We're rooting for you, Dylan!! Get well soon!