It's been a long time since the Bruins have advanced in the Stanley Cup Playoffs, so let's have a refresher of the rules. Like the NFL and NBA, the teams are reseeded after each round. The Bruins, as the #1 seed in the East, will face the lowest seeded team that remains.
The #7 Rangers hold a 3-1 series lead over the #2 Capitals. If the Rangers win the series, they will meet the Bruins in the next round.
If the Rangers lose their series, and the #6 Hurricanes beat the #3 Devils (series tied 2-2), then the Canes will meet the Bruins in the next round. In my opinion, this would be the best matchup for the B's in the 2nd round.
If the Rangers lose their series, and the Hurricanes lose their series, the Bruins will meet the winner of the #5 Flyers/#4 Penguins series. Right now, Pittsburgh holds a 3-1 lead in this series.
There is no way the Bruins will face the #2 Capitals, or #3 Devils in the 2nd round.
So odds are it will be Bruins/Rangers in the Conference Semifinals.