at least for the Avs, it really, really isn't. they can't afford

Avs will need Kuzy's cap hit down to $5M or less. Shouldn't be a big issue for WSH, as they have plenty of cap space here.

You could double that offer and it’s not enough to trade him to a division rival

I think the most realistic Kuznetsov trade would have Kuzy passing through a rebuilding team like San Jose, Chicago, or Arizona. Caps and Avs each throw in a 3rd or so, and the pass-through team retains 2.8M. In OP's scenario the Caps have enough room to handle the retention themselves, but there's a good chance they go after someone with a higher cap hit than Konecny.

With Lansdeskog on LTIR and depending on what happens with Nichushkin... they might be able to

Nuke is back. Even with the Landeskog money, after Kuzy leaves ~ 10mil for 10 skaters. 2 of which are RFAs worth around 6-7mil together. Kuzy is by far the most expensive 2C option the Avs could possibly end up with. Even if they moved a defenseman they would cap strapped after Kuzy. There is zero chance just on a logistical stance.

That's fair