Doesn't have to be a disgruntled star, sometimes teams just decided to move on from their vets (especially when they're aging, injury prone, or the team has plateaued.) I wouldn't be surprised if the Bulls decided to part ways with Derrick Rose, especially since they have a new alpha dog in Jimmy Butler. Rose has 2 years on his contract, this season is the time to trade him if you want to get anything in return.
While most think Miami is a top 4 team, I wouldn't be surprised to see the end come sooner than expected there. Wade can fall apart for good at any moment. I pretty much view them as the 2013 Celtics or 2013 Lakers or 2014 Nets (if not this season than next), and some time soon they're probably going to have to shake things up. Pat Riley has traded away or let walk away just about every big Heat player in his 20 years in South Beach. Miami's "window" and Chris Bosh's contract don't really match up, he'll be traded before his contract is up. Probably not this year, but maybe next.
Is Carmelo going to finish out his contract in New York?
I wouldn't be surprised to see the Raptors blow it up. Kyle Lowry and DeMar DeRozen could be moved. DeRozen has a player option next season for $9.5m, it's probably a sure thing he's opting out. If Toronto decides they're sick of 1st round playoff exits, you might be able to get him without giving up too much.
While not as sexy as most dream scenarios, I wouldn't mind a C's team that traded for DeRozen this year and traded for Chris Bosh next year.
If I really stretch my imagination (and the C's get some lottery luck) maybe I can even dream up a scenario where the C's can trade for Rose, Carmelo, and Bosh before the start of the '17-'18 season.