No players on any roster are un-tradable, so yes.
Trading them for any expiring contract should be off the table. Hertl, Domi, Giroux, Kessel, Giordano, Chariot
Trading them for anyone over the age of 30 with 1 or 2 years left on their contract should be off the table with maybe with Pat Kane the exception.
I wouldn't include either in a deal for JT Miller. Unfortunately there's too much smore there with Miller so i think Kakko could be in a deal there.
If Chychrun was the target, the contract makes so much more sense. The need of a potential top pair or top 4 LD is also there. It also leaves another hole at RW. That seems to be the top 6 position that needs a filling. I like Chychrun, and i think that might be a good fit here. I also think the Rangers can land him w/out giving up one of the aforementioned. Chytil, 1st rounder and maybe Gauthier?
Both Kakko and Lafreniere are 20 years old. They are still figuring things out in big market team. They are getting ice time and looks with some of the best players in the game currently. I think it's just time that they need.