Maybe I'm being stupidly optimistic, but I still think if you just fix the defence (even without getting a big piece), you'll simultaneously address a lot of issues with this team. It's biggest flaw with this roster, they need more offence from the blueline. Without Sekera, they lack a defenceman that can with certainty score 30 points, let alone 40 or even 50.
A better transistion means the forwards get the puck in better spots to attack, and that you also spend less time chasing in the defensive zone (which helps the goalies). Hell, better offensive pointmen would also help get the puck on goal, which helps the guys who need to go to the net to score (RE: perhaps they could also bounce the puck in off Lucic's a$$ once and a while.)
Bring up Bear, get a proper offensive 2nd pairing defenceman, and maybe upgrade the 2nd line RW. Make those changes and I can see this team makes some headway (for example, add in Green + Vanek from Detroit).
RNH-McDavid-Rattie
Rieder-Draisaitl-Vanek
Lucic-Strome-Chiasson
Khaira/Caggs-Brodziak-Kassian
Khaira/Caggs
Klefbom-Larsson
Nurse-Green
Russell-Bear
Garrison
That looks far more solid to my eye. Myers, Vatanen, Faulk, Shattenkirk, and Ceci would all fit this mold too, and none would/should cost an arm or a leg to aquire...