so does losing a retention slot and 5+mil for nothing

In TOR EK65 would be on the top pairing and probably QB PP1 lol

Yes, having San Jose to pay $21 million not to play for them should cost a lot but you have to take into account which portion is an overpayment... So if both agrees that EK's cap hit should be 9.0 for example, 2.5 in retention is San Jose's sunk cost

At $11M, there are currently 2 teams capable of absorbing his cap hit, neither of which are contenders that EK is waiving for, so there is no market.
The question is how much does SJ have to absorb to even create a market where a contender can realistically fit him in.

You have to go all the way up to a cap difference of $4M to even get 2 possible destinations (Detroit and Nashville), and there are still no true contenders, meaning no market yet.
The only realistic way Karlsson is moved to an actual contender, is if the net change in cap can be reduced to $2-3M with a combination of retention and contracts included.

For example: You could take Campbell from Edmonton + Retain $3M on Karlsson and make them a possible destination, but that has to be the starting point of any negotiation just to bring them into the conversation, so you aren't getting (significant) assets for either taking Campbell or the retention. Any actual value in trade begins from that point.

That could open up once the cap begins increasing, but the current market is tapped out so that's closer to the current reality.
The risk there, is that EK's value, performance, or health declines before there is enough money in the market for a more reasonable deal.

Not really no

Then there's no deal. Why trade your best and most import player for nothing in return. Carolina, or any team trading has to give away cap, karlsson is a phenomenal player and San Jose have to retain $21 million. Do you know how much that is?

They have to retain on a player that's 33 with injury issues? They'd have to do that if a team had room for EK. They had a chance to maximize their return for him but wouldn't retain more than 20% at the deadline. As soon as they realise they're going to need to eat about 50% to move him, they'll start getting the return they want