By Matthew Geagan, CBS Boston

BOSTON (CBS) —  The Boston Bruins lost their final game of the season, which is always a disappointing way to end any year. But it’s getting a lot harder to come to terms with such abrupt ends, because the team isn’t sure how many more opportunities they’ll get as a group.

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This season may very well have been their final chance at glory.

There was already a massive offseason shakeup following last year’s second-round ousting, with the Bruins moving on from longtime captain Zdeno Chara. Moving on from such a central piece of the team’s foundation was the first dose of reality that the core’s run wasn’t going to last forever.

There are even more questions about the core heading into this offseason, following Boston’s second-round ousting by the New York Islanders in six games. Coming up well short of another Stanley Cup run has everyone in the dressing room feeling that they just let another opportunity go to waste.

“It’s disappointing. We expected a longer run in this room,” said Brad Marchand. “We felt like we had a group that could go really deep this year.”

While the Bruins have an extremely young defensive corps, the leaders on offense are no spring chickens. Captain Patrice Bergeron is 35. So is David Krejci, and goaltender Tuukka Rask is 34 — both of whom are unrestricted free agents this offseason. Rask didn’t go into it Wednesday night, but he’ll likely be going under the knife this offseason after dealing with injuries to close the season, adding another giant question mark to his future.

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With those three on the back nine of their careers, it makes each season that ends on a down note all the more difficult to digest.

“That core is getting older one year to the next,” said Bergeron. “It’s disappointing that way. You have a good team, you have opportunities and you know they don’t come that often, especially later in your career. You want to make the most of them.

“I’ll take it a year at a time and see what happens,” added Bergeron, who is signed through next season.

Rask was noncommittal about anything and everything after Wednesday’s Game 6 loss, but he too admitted that time is not on their side.

“I think it’s the same answer as every year. We’re all getting older and we’re not going to last forever,” said Rask. “So it’s definitely closing at some point, for sure. We have great leadership, great veteran guys, and we try to build a new team every year and come together, and I thought we accomplished that pretty good this year.”

It’s sacrilege to think of Patrice Bergeron playing anywhere but Boston, but there is some serious doubt that both Krejci and Rask will be back next season. And the fact that this core group has just one Stanley Cup win, while coming up short in two other Final appearances, over the last ten years may be an indication that it’s time for Don Sweeney to rip off the Band-Aid and start new with a fresh core. Since winning it all in 2011, the Bruins have missed the playoffs twice, been ousted in the first round twice, and been sent home in the second round four times.

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Big changes are likely coming to the Bruins this summer, and those changes may start with a some of the longtime faces of the franchise.