I would love to find out what Marc Bergevin would be willing to give up for Letang.
I know he's a right defenseman and not a left defenseman, and Montreal is clearly in the market for the latter, but Bergevin and Canadiens ownership seem to be on a mission to save face right now. Adding a Montrealer and Stanley Cup winner would be viewed locally as a major coup (NO MATTER what they surrender in return). Also, they have the cap space to pull it off and would also need to spend it to save face with the fans.
If Bergevin would be willing to deal his 2018 first, plus Galchenyuk and a young defenseman like Mete or Juulsen, I think you have to pull the trigger. Basically, we're talking about the return that Joe Sakic is hoping for in exchange for Matt Duchene.
Anything less, and I agree with the notion that Letang's value isn't high enough right now to deal. Wait for him to start playing well again, then see what's out there.
JR is never afraid of the bold trade, and this season he just might have to make one of those.