I don't see how this changes anything for the Bruins.
We knew Florida would be good. Good teams don't always win. Especially in the NHL. Look at Colorado. Look at Vegas who had less points than Boston. They're not going to cancel the season because Florida added Brady.
We also knew Boston wasn't/isn't one player away from contending. It would be surprising if Sweeney was out there trying to cash in all his draft picks and/or best prospects to add 1 big sexy name. Then what? You're still 3 high-end players away from being a Cup favorite.
I still think the Bruins are going to try to improve the team that takes the ice in October, not because it makes them instant Cup contenders but because there are several steps to climb to get to that level, and improving the team gets them one step closer. I also think Sweeney is going to try to do that without sacrificing his best young assets and picks.
Personally, I'd like to see them take a chance on a couple high risk/high reward moves. They need more big wins like Haula for Zacha, Geekie as a UFA and Carlo for Minten...