What intrigues me the most about Kotka is that even if he doesn't work out as a 2C, he's a very affordable 3C and as the cap rises that only gets better.
And he's already a pretty solid 3C. Very strong defensively, struggles offensively right now but I think he'll figure that out. If his offense doesn't improve at all from right now, you've still got a ~30-35 point 3C with elite defensive ability.
At $4.8M that's basically the going rate for solid 3Cs already(Pageau and Gourde).
That being said, I dont see any reason why Carolina would get rid of him. They can easily afford to wait on his offense for now and just keep for the exact same reasons why we would want him. Solid player on a great cap hit going forward, no reason at all to move him.