This probably won't happen because the teams are cross-town rivals, but I think this would be a great fit on both sides.
RJ is highly thought-of, but he just doesn't fit in NY. The mid-three had a negative on-off together last year, but both Randle and Brunson were big pluses without RJ. RJ, however, had a -1.21 net rating when he was on, while the Knicks had a +9.67 net rating while he was off last year. He is still highly inefficient, and his development seems to have stalled. He needs a change of scenery and probably needs a better development coach than Thibs.
In this deal, the Knicks fill their weakness on the wing, with DFS stepping into the starting lineup at the 3, to provide some 3&D to make the starting unit more coherent. Thomas should give the bench some scoring pop, and him along with Sharpe give the Knicks a couple of young players to develop, which should help with the perceived value disparity between DFS and RJ.
For the Nets, the KD and Kyrie trades left them with great supporting pieces without any lead stars. Bridges showed signs of emerging as a potential star late in the season, but they could really use a second addition. The Nets would be able to give RJ an opportunity to play with a much better spaced lineup, with shooting at every position aside from center. A off-ball shooting 4 like Cam Thomas would be a much better fit next to RJ than a ball-dominant interior player like Randle. Bridges and RJ could give the Nets a solid young duo to anchor their group of role players.
So, who says no?