Been pondering this myself. There are very limited options when it comes to a CF because no one, at the top level, want's to come in and play second fiddle or even have to fight with Isak for the starting place. Either it's got to be a young prodigy that no one else is after, another role of the dice with someone like Osula or an older player who can do a job and happy to be in a winning team picking up a decent wage like DCL.
The fact there are still rumblings about Wilson signing a new "pay as you play" contract is probably showing that we don't feel there's much out there, worth spending £20-30m (at a minimum), to come in and warm the bench behind Isak. DCL depending on wages will do a job and at 28 gives you a five year younger version of Wilson basically. The only draw I could see would be to sign him on a free and then manage to sell him in a year or two for a few million to boost the kitty.