You're not replacing Bergeron and Hall's goal production, that's just not possible given the cap constraints.
The Bruins scored 305 goals last year, which was second only to Edmonton. That's not repeatable. Bergy and Hall combined for 43. Just subtract that from 305 and you're at 262, which is on par to what Pittsburgh scored last year and only 4 fewer than Carolina. Let's say you get 10 extra goals between JvR, Coyle, and Geekie, that brings you to 272, and you know who scored 272 regular season goals last year? The Vegas Golden Knights.
Flipside, Bruins only allowed 177 goals all year, leading the league by a huge margin. You've still got both goalies and the full defense back as of now. if Bergeron's not there it puts a dent on your overall team D and PKing, but say we allow a whopping 50 more goals as a result, that's 227. You know how many the Golden Knights allowed? 229!
I don't think the team is set up to contend in the playoffs unless some kind of deadline magic occurs (and they can't afford to trade any more futures), but the more I look at it from a macro perspective, I think they're still comfortably a playoff team after an 82 game regular season.