Why would Orlando trade him? Cost controlled, young, and provides a skillset they need, starting or off the bench.
Overloaded with young/talented wing players and he's restricted free agent.
They can't pay him and keep Tobias Harris. Well they can but that would mean no future cap room for free agents and no significant expirings, so the consensus is that one of Harris or Fournier won't be with the team after this summer.
With Gordon, Hezonja, and Oladipo already on board, I think I'd look to trade Harris if I were them. He's a good player, but I think he's more of a small-ball 4 than a 3, and you can't play him with Vucevic.
Plus, Fournier should be cheaper (around 10 million per season), so it'll help them afford other guys later.