The Terriers are playing PWR #32 Merrimack in a best-of-3 to open the HE tourney. Obviously they need to advance to have a chance, but a sweep would provide some insurance. Getting swept would certainly end their season, and winning only 1 of 3 would most likely do the same.
If they beat the Warriors, we still don't know their next opponent since the first-round winners are re-seeded for the second round. But for the sake of argument, let's say top-seed UMass-Lowell gets past Maine while 2-seed BC beats Vermont. The Terriers would then play the current #5 Eagles at Conte Forum. Win that series, and BU is pretty much a lock for the field of 16, and would probably be a third-level seed (#9 thru#12). Lose it in three, and they'll still be on the bubble. Get swept, and they're probably toast.
Should either Vermont or Maine manage to pull off a first-round upset, BU would then host the winner of Providence-UNH in a best-of-3 at Agganis. UNH enters the HE tourney #6 in the PWR. A Terriers win, whether it's a sweep or in three games, almost certainly puts BU into the NCAAs. A win and 2 losses will leave them on the bubble. Get swept and they still have a slim shot, but they're far more vulnerable to being displaced.
If they play #22 Providence in the 2nd round, it's much simpler. A Friars win almost certainly makes PC the new bubble team ahead of BU, and the Terriers are done. A BU win would really solidify their chances, since they'd be getting at least one more game against either BC or UMass-Lowell in the semifinals.
Since the PWR is formulaic rather than cumulative, a lot will depend on how some of the teams behind them in the PWR end up doing in their conference tournaments if BU fails to advance past the second round of the HE tourney.
#17 Union, which has a bye in the CCHA, will play either Harvard or #20 Dartmouth in the next round. If it's the last-place Crimson, winning those two games won't help Union's PWR much, and if they lose a game it could be quite damaging for the Dutchmen. Dartmouth's a far stronger team than Harvard, but they're in the same boat as Union (i.e. in contention for one of the final NCAA spots). A two-game sweep by either would give a nice PWR boost, but a three-game series between them would negate some of the advantage for whichever school prevailed. The winner would then need to beat #1 Quinnipiac at least once to make any headway in the PWR. Advancing past Quinnipiac would be huge for either team.
#18 Wisconsin's WCHA tournament opponent won't be known until after #8 Denver & cellar dwelling AK-Anchorage play tonight to close out the regular season, but it'll likely be against either Colorado College or Neb-Omaha (currently 30th & 31st in the PWR respectively). Obviously they'll need to win that opening best-of-3 series to have a shot at the Top 16, and would likely need to win at least a game in their next best-of-3 series matchup to stay in contention.
#19 Alaska needs to win tonight against Michigan State to advance in the CCHA tournament, or their season is all but over. But if they win, they'll move on to face #10 W. Michigan for a best-of-3 in Kalamazoo.