If it just comes down to a change of scenery, and we want to make a deal during this season for a RD, why not do Ritchie + Dermott + prospect for Myers + Cousins with Nashville?
Money in vs. money out is practically identical (50k added for us). Myers has sucked in Nashville but had a ton of promise, not much unlike Dermott (who is almost the same age). Myers is getting healthy scratched a lot, so maybe Dermott has more luck for them (even as a RD). We get a guy we can try out for the rest of this year at RD with great upside, but is also great for our depth, and worst case we should be able to find a team to take him for next to nothing like we would need to do with Ritchie anyways. If he does well, we can move Holl in the offseason for a nice return and we have Rielly-Brodie, Muzzin-Myers, and Sandin-Liljegren as our pairings for next year.
Cousins is not necessarily struggling, but he is capped as a pesty 4th line forward anyways. People want Hagel badly... Well Cousins is that but older, a pending UFA (who maybe we considering re-signing), and a local kid with a Soo connection. He would fit well on our 4th line with Spezza and Simmonds, if we want a more "physical" line or if Engvall needs to play up when Kase inevitably gets hurt again. Ritchie has more upside than Cousins, should be able to replace what Cousins brought to Nashville but in a larger package, and considering Nashville is a team that plays Harpur and McCarron with regularity, I suspect they would find a nice role for Ritchie.
Give them a decent but expendable prospect to sweeten the pot and I think you have a deal the Leafs can get behind to improve their team without giving up anything major off of their roster. Win-Win proposition that seems like a match made in heaven really.