Hamilton is young enough I doubt he has the rights to even get extended an offer sheet. Cannot say that outright, but I would be shocked if he qualified for it.
IIRC wasn't Vanek offer sheeted after his ELC? Wikipedia says that he was but I'm not quite sure what his age was when he got the offer sheet. I think O'Reilly would be a similar case as he signed Calgary's offer sheet in the 12-13 lockout season. So I don't believe Hamilton couldn't be sent an offer sheet.
I know the reason that Smith/Krug couldn't be offer sheeted was because of the fact they had not met the games played requirements to get all of the rights a normal RFA would have, those games played requirements being 10 games of professional hockey in 3 separate years. Here's an
article that explains the CBA rule on it.
I'd say something along the lines of 7 years x 6.5 Million or 5 years x 6 Million would put the Bruins in a mighty hole. If they accept they're unable to sign any of their depth and would surely be stuck in a bit of a hole until the cap rises. The only issue is that you calculate the pick(s) you give up by (Total cash/Years) except if there are greater than 5 years. For the 7 years x 6.5M it would be looked at as a (45.5/5) 9.1M cap hit and the Wings would have to give up 4 1sts.
If we can get by giving up less than 4 1sts I'd be able for it. Hamilton would give us a legit #2 right handed dman for the next 10+ years and he may even develop into something more. Ideally we'd sign Nyquist to a long-term deal before we sign Hamilton as the kids may demand a similar pay scale.
There would be little downside to sending an offer sheet except for the fact that it would just make the Bruins more likely to retaliate but we don't really have a player of Hamilton's caliber coming up so we should offer sheet away.