Well if he says no to a trade then he's definitely not coming back next year.
I'm not worried about him declining a trade for that reason alone.
In fact I think that if he's getting traded, he's getting traded at full cap hit for someone at full cap hit (like Domi) then he's getting flipped somewhere else.
Like I explained before, it makes no difference for the Hawks to retain on Domi or retain on EJ, either way it takes one retaining slot. So if they don't have to retain on Domi, they can retain on EJ and flip him for a pick.
Edit: I said Domi but it could be Horvat at full cap hit too.