We have no idea what the potential return for Dumoulin is or what the potential solution is to fill his hole.
Dumoulin is a great defensive defenseman, but he's a dime a dozen in terms of replacing his impact by committee. I'd prefer to keep him, but if we can get a legitimate 3C or a highly touted prospect that is NHL ready for him. Bye!
The problem with trading Dumo is the same problem with trading Rust. At their current contracts they are way more valuable to the team, then what they could get the team in a trade. In order to get the needed cap space, the players that should be traded are in this order:
1) JJ - We can all hope and dream, but from what we have seen and heard, JR and Sully like him...gag me
2) Horny - it hurts but $5.3 is too much for an aging 3rd line winger, he would be more valuable on a team that is weak on RW depth and can use him in the top 6
3) Petts - if JR brings in another expensive LD, something has to give
4) Zucker - decimates the Pens LW depth and we haven't had him for long, but he could have a good return and/or save $5.5M
5) Rust - sell while his value is high, but really you are not going to get any where near Rusts value at $3.5M
Letang could probably be in there somewhere, but then the team does not have a #1D and who knows what season 2 will be like for Marino. Dumo is the only top pairing LD this team has. Petts is good for second pair or 3rd, but no one wants him playing top pair minutes. If the trade goes through, the entire league would laugh if Matheson is on the top pair. We all know what JJ does with Letang, so we can't go there again. Dumo should be more untouchable than Letang in my opinion.