My one concern is that Riley will try to tank next season, just to mess us up.
Riley can't tank nearly enough next season to get near the Nets. Compare their starting lineups, and we'll assume Bosh is done.
Dragic > Lin
Richardson > Bogdanovich
Winslow > RHJ
Williams? < Booker
Whiteside > Lopez
Tyler Johnson and Wayne Ellington, while nothing special, are better than anything the Nets have on their bench.
I don't think the Heat will be good. Frankly I expect them to be a bottom 8 team. But it would take a lot for them to drop below the Nets, who shouldn't win 20 games. There's a big difference between not good, like the Heat, and miserably bad, like the Nets.