ANA isn’t interested in either for anything at all

Sure - switch the team, add in a pick or a B prospect, whatever. The Kampf deal is moveable, and Timmins will have value to a number of the weaker teams around the league. Not impossible to get out of both contracts by any means.

I don't think that the Kings are interested in exchanging two seasons of Adrian Kempe for one season of Mitch Marner, especially in light of their respective cap hits and the Kings' cap situation.

So the "big changes", "actual re-tool" is moving one key piece and returning the vast majority of the current roster?

You can probably move Kampf, but at his term/AAV, it's as a cap dump. Teams know the Leafs need the space and want to move him, so they're probably not giving up assets for him. You might be able to move him to a contender if you attach a 6th or 7th, and you might get a 6th or 7th for Timmins (who's also an overpaid 7/8D).

Marner is going to be...tough. If that's the piece Toronto decides to move, he's either dictating exactly where he goes with his NMC (a la Tarasenko) or you're sending him to a team as a pure rental. I think that return would be incredibly disappointing.

TML aren't moving Matthews (obviously), Nylander (with a new extension), Tavares (again, full NMC and no one is taking that deal right now), or Reilly (full NMC, best D-man, and 6 years to go). Honestly, I don't see a way to revamp this team without taking a massive loss on trade value, the best chance is moving auxiliary pieces and signing upgrades.

The time to make changes was last offseason, pre-NMC for Marner/pre-Nylander extension/pre-Matthews extension. Shanahan was resolute in saying no. Now you're stuck. Toronto had better hope firing Shanahan/Keefe/Treliving and overhauling the roster outside of the big five is enough.