I don't 100% know that DJ will garner a 1st, but we should find out.
I think generally he is a low-end #1 WR and got paid accordingly last offseason. That deal becomes a bargain for a team to trade for him because the Steelers eat the signing bonus.
The issue with Diontae here is he makes huge gaffes (fumbles, drops, running backwards) at the worst times. These are back-breaking issues to this team and the mindset of this offense. I'm betting, however, that some other teams will overlook the timing of his gaffes and focus on the 95% of plays where he's good and often open, as a superlative route-runner.
I could also see us keeping him, though at this point I think he is regarded as a loser within that locker room. He needs a fresh start.