I kinda am because the receiving team is going to want the full discount of 75% and not give up anything. That puts the onerous on the Sharks to sweeten the deal for the middle-making team.
There's also on-ice issues such as leading the league in PIMs twice in a row, and more importantly, Kane comes with a bullseye painted on his back for attacking a ref.
If a team doesn't get a sweetened deal, meaning the Sharks contribute all the sweetener, they'll be more inclined to just wait until after the buyout, imo.
Teams in a win now mode wont want to wait, especially if they could lock him up for a well under post-buyout market (say @ 2.5M). Plenty of scenarios where a 3rd team picks up as much as 2.5M in cap hit for, as you inferred, something sweet. One idea floating in my head revolves around AZ, because they only have six players signed next season, with 50M in cap space. They may want semi-decent wingers to help them reach the cap floor:
Toronto Pays: Ritchie + 2nd and receives Kane @ 2.5 M/year (same salary as Ritchie, so completely salary neutral for them).
San Jose pays: LaBanc (assuming he heals before the TDL) + Kane (2M retained) while receiving Toronto 2nd + Roussel
Arizona pays Roussel + retains 2.5 M on Kane while receiving Labanc + Ritchie
Upgrading Ritchie to Kane at the same cap hit is likely worth the 2nd to Toronto. Spending + 2.5 M in cap for 3 years (which helps them reach the floor) while picking up two decent and still young wingers may be worth it to Az. Roussel is a pending UFA so it is just pure money savings to offload him in this. They could even offload ritche next season, and labanc the following for more picks.
For us, picking up a 2nd for LaBanc and offloading Kane with only 2 M in retention would be a cap correcting homerun.