Realistically, an upgrade on Demelo at RD, but that would mean also moving one of Demelo/Heed.
What the fans probably want is more picks and prospects as well. We have almost no defensive prospects apart from Jeremy Roy who has had like three season ending knee injuries already, and Ferraro who actually looks pretty good.
I think there would be interest in Columbus for a player like Tierney, as others have echoed in this thread. While our RD depth chart is essentially Jones and Savard, I think anyone outside of Werenski and Jones could be moved (while others have said Savard can’t be moved because of this lack of RD depth).
Assuming Cole is extended I think the one of following players could be moved from the D group for an upgrade at forward:
Murray, Nutivaara, Savard, Carlsson, Gavrikov. I believe the first 3 are top 4 capable right now. Gavrikov has one more year in KHL but certainly has that upside. He was expected to play in Columbus last season before he signed a two year deal in KHL (stated he wanted to be in the Olympics). Carlsson was 29th overall, and hasn’t looked out of place at the NHL level, but he was drafted at something like 6’4 175 and spent last year mostly in the AHL, but is expected to be an integral part of the team moving forward.
There are others lower on the depth chart or in the system that could be mentioned but if we are talking about people that could play top 4 roles within the next year, I think CBJ have at least 5 options that could work.
If the Jackets re-sign Cole as expected, and Gavrikov comes over as expected, the season after next, we could have 8-9 more than capable defensemen, which is simply a luxury when we are lacking experienced center depth.
19-20 season:
Werenski-Jones
Murray-Nutivaara
Cole-Savard
Carlsson-Gavrikov
Of course I have no idea how highly some of these players are valued around the league, especially relative to Tierney. But I think there is a deal to be made somewhere.