Some guys you know are going to be gone, so you can go ahead and cut them on Friday.
But if a team thinks a guy they don’t need might have value, you can bet they’re going to wait until the last minute.
The Eagles are deep enough at receiver they probably wouldn’t be able to/want to keep Johnson.
He’s undersized, but he’s also shown enough as a special teamer and a wideout that he might interest someone. He caught 19 passes for 256 yards for the Eagles last year, and might be worth the obligatory conditional late round pick to someone.