I would listen with Vatanen as the main piece coming back. I'd also be interested in Fowler (probably more interested, honestly).
If we move Drouin, I'm not too worried about the cap that's coming back. Obviously I don't want a bad contract, but whoever it is is someone we can figure out how to squeeze in (probably just by moving Garrison).
Edit: Also - this is the last year of our cap hell. After we re-sign Johnson/Palat/Drouin(?), we don't have any expensive players coming up for a new contract for two seasons, and by that time we'll have lost some of the dead money on the books (Carle's buyout, Callahan will have one year left on his deal, Coburn's contract is up, etc.). As long as we don't get handcuffed with a new bad contract in the intervening time, I think we are fine.