This is clearly a "Bryce is done in Carolina" move if I've ever seen one.
Trading Diontae for a fourth or more (what he's worth at the least) would be acquiring assets as we're in a hard place. However, trading him for absolutely nothing of value while you have half a season left with a floundering rookie quarterback? Yeah, they're done with Bryce.
If Diontae is healthy, and plays up to his potential, he's a number one receiver.