I originally prepared this for the EK to Dallas thread, but it is more appropriate here:
After giving this some thought I actually think that giving teams permission to negotiate with Karlsson is a blunder by Dorion. That does not actually give Ottawa any leverage and in fact it just gives Karlsson all of the leverage.
So right now Karlsson has the ability to wait until UFA and choose the one offer that's best for him. Dorion did Karlsson a huge favor and said he's allowed to do that now and at the same time negotiate that 8th year. I guess he's hoping Karlsson reciprocates by agreeing to a few teams and letting Ottawa choose which he goes to.
Here are the possibilities, ordered ascending by leverage Ottawa has in that scenario:
1. Karlsson signs with one team, takes the best offer as though he was a UFA. That team does not have to outbid anyone for the trade, and only needs to put together a proposal that is better for Ottawa than one year of Karlsson - so one year rental value and no competition for the buyer, a disaster for Ottawa.
2. Karlsson agrees with 2-3 teams, and lets Ottawa choose where he goes. Those 2-3 teams only need to outbid each other, and we are probably talking about contending teams whose most valuable pieces are untouchable pieces of their core. This is like extended Karlsson with a full NMC.
3. Karlsson agrees with a bunch of teams, 5+ and lets Ottawa choose. Same as #2 but this includes the possibility a team with good prospects is included, and Ottawa may be able to negotiate a good return. Essentially, this is Karlsson with a partial NTC
4. Karlsson agrees with everybody and lets Ottawa choose where he goes. 30 teams involved and bidding against each other. This is equivalent to a signed 8 year Karlsson with no NTC. This scenario is a pipe dream.
In summary, I consider scenario #2 to be the most likely, and #1 to be a distinct possibility. Dorion might have had more leverage without giving teams the chance to negotiate with EK, because then he had 30 teams bidding for a 1 year rental with the opportunity to negotiate for that 8 year of the extension. As it is, he's really just banking on Karlsson doing him a favor and giving him several options to negotiate with.