Avs should take Ryan for Ott's 2019 1st and removal of the conditions on the 2018 1st.
Ryan must agree to waive his NMC (for expansion draft only)
Ryan's NMC is already not enforceable in expansion drafts. He did not have to waive for Ottawa to expose him. The NMC for whatever reason was a modified one written in a way that makes it so that it only pertains to Ryan being sent to the minors.
So long as we do not win a top 3 pick in the lottery, I would do what you outlined in the OP if Karlsson is willing to extend in Ottawa. But, I think value ways, it's skewed against COL. I'd be surprised if a team was willing to take Ryan that cheap.
Giving up let's say 5th overall in exchange for 2019 OTT 1st+COL taking Bobby Ryan is unfortunately great value for Ottawa which feels odd to say when you're talking about giving up a top 5 pick.
I would expect it to cost us one of our best pieces with nothing coming back, whether that's our pick as one of the top picks in the draft, Thomas Chabot, etc. At that point, so long as the offers for Karlsson are strong, I think we're better off just bundling Ryan with Karlsson and re-tooling/rebuilding because I don't we can compete with Karlsson @ market value, and Ryan+Gaborik+Phaneuf+Mac as dead money under a 68M budget.