This team could re-tool this roster and still be a decent team but that involves the obvious of firing Sullivan and K12 Kyle making some quick moves for some players that should have been moved this summer.
Like Pettersson, Eller, Acciari, Nieto, and Rust.
I don't mind keeping Bunting and Rakell as I think they're very good buffer's for the top 6, Rakell with Sid and throwing DOC would be the better balance, Rust would fetch a very good return, Eller should have been moved last TDL, Nieto and Acciari for literally future considerations would be incredible at this point and Pettersson is not someone I extend and I don't think Dubas will to be honest, it doesn't make any sense to.
It's fine to keep some older players and mix in more youth. Hayes moving to wing for example on the 3rd line is fine with 2 younger players, the 4th line being maybe 1 veteran at most with a younger set of players is also better to roll through.
A new coach could fix some of the other issues just by not deploying the absolutely asinine system Sullivan thinks is bullet proof.