I like the idea of going hard after Subban. He's not the player he was, but he's someone that can still insulate defenceman lower on the roster.
If it takes something like the 8th, Benson/Yamamoto/Puljujarvi/Jones, and Sekera (for the cap). Then I think that's the kind of trade you need to go for.
If you upgrade the offence from the backend, then that helps your forwards even if you don't upgrade them directly.
Draisaitl-McDavid-Kassian
Yamamoto*-RNH-Puljujarvi*
Lucic-Khaira-Gagner
Gambardella-Brodziak-Russell
Cave
Nurse-Subban
Klefbom-Larsson
Russell-Jones/Bear/Bouchard/Persson
*I'm suggesting Yama and Pulju, as they still have the highest upside in my eyes; however I have that second line as an open competition between those two plus Benson, Marody, and even Gambardella and Currie (basically whoever doesn't go in my supposed Subban deal). Gagner drives the offence for the soft minutes parade/3rd line, and the 4th line gives you a couple cheap grinders to rotate through for defensive starts.