That opinion ain't fact. And even if it was I'd sooner retain the known quantity in Tanev than flip him for a second round lottery ticket. I don't imagine we'd have much trouble signing him to an extension so it's not as if our hands are tied and we've got to get something for him.
If that's all we get, keep him. Prices would be likely to go up near the deadline anyway and he's an easy contract to fit with retention as a rental. I also have no issue with keeping him around in a role similar to Salo.