Buffalo gets older, and drops in the draft. However weak the draft is, and however similar the 8th and 11th picks will end up being, is that maximizing Kane's value? They could probably retain 50% and get a 1st round pick for him, without giving up their own. If I'm Buffalo, I'm not giving up the younger player, and the higher pick, and taking Clifford to even out the cap. There has to be a better deal for Kane out there.
They can get one of those two in the expansion draft, so they're dropping two spots in the normal draft to get either Lewis or McNabb? What's the upside for Vegas? They'll have a chance to get plenty of players like Lewis or McNabb in the draft. If you gave Vegas someone they couldn't get in the expansion draft that was good, plus Lewis or McNabb, and the pick, that might be something. If Vegas took Lewis in the draft, would it take a 1st round pick to get McNabb in a trade from the Kings in addition to that? That's essentially what your deal is; a 1st for McNabb and a 1st. The Kings got McNabb and a couple 2nd's three years ago, for a couple prospects that weren't 1st round picks, and McNabb hasn't really elevated his game all that much.
It all just works out way too well for the Kings. They get a guy that scored 28 goals this year, they clear cap space, not just for next year, but possibly future years if Kane doesn't work out, and they move up 5 spots in the draft, and maybe add a 3rd rd pick, and can maybe sign a free agent. That would be quite the coup.