What might Canucks want for Tanner in a trade?

You would have to get his permission before a trade as he is the only player with a NTC.
Half a point player per game. Can play in Top6 but certainly decent third liner on a very decent $3.25M cap hit.
Second and a prospect should do it.

I would say a 2nd or 3rd. As said above Pearson has control and the Canucks need the cap space.

A 2nd or 3rd round pick should be fair value for Tanner, just as @Faceoff said