Hmmmmm, I've heard this before.
Even in your post though, there are a significant amount of moving parts that you feel need to happen to get a kick at the can. More than what happens in a typical offseason, that's for sure. Subtract two top 4 defenders, add one, add a top 6 winger, shop your starting goalie. That's blow it up stuff you're talking about....
and all needs to be done within a significantly shortened offseason.
Say for example, Colorado calls you up and says "Hey, we're all in, we'll give you Compher, Newhook, and Byram for Bergeron", I sure as hell am not saying no to that because we want a feel good story of Bergeron riding off into the sunset here.
In my mind, I agree that no one is untouchable ever, but especially anyone above 30. The Bruins will be around much longer than anyone on the roster, so the goal should always be improve the franchise.