With respect to the Bruins doing a rebuild or retool, I would point to Washington as a worthwhile case study of alternatives. The Caps looked to be heading in the direction of Pittsburgh, winding down an aging core where a key player or 2 were drifting away every year and reaching the point where they were a bubble playoff team at best. It looked like their window was about to close. Instead they have turned things around big time and I don't think that's a mirage. The Caps made numerous additions and they have all worked well or great. It started with Strome and continued with Dubois (who wanted that guy 6 months ago?), Chychrun, etc. They added 5 or 6 players who have replenished a moribund roster.
I don't know if this is what the Bruins should attempt but it is something to consider before fully embracing the "trade everybody" and "blow it up" direction. Making a retool (vs rebuild) work 100% comes down to bringing in the right players. Washington looks to have executed this really well but many other teams have tried and failed (see Nashville). Also relevant is that I am not 100% sure that handing a bunch of additional 1st or 2nd round draft picks to this front office is any guarantee of a return to greatness in 5 years. But standing pat is not the right choice so you've got to choose one of these paths.