Well if a team loses a top player this year they only get one pick as opposed to two in previous years. And I think they have to offer the player 13.5 million to even get the one pick. So some of the suckier teams could end up with nothing for their player. So if he is a pending free agent that they have no desire to sign there is no reason to not trade him.
There's always risks/rewards on both sides, but with the Wild Card teams only guaranteed one game from here on out, and not necessarily a home game, I still think the risk is greater for the team that's trying to pick up the guy in the last few months of his contract this season.
We're certainly not going to see the top prospect type deal like we did last season (say, Zach Wheeler for Carlos Beltran) if the team that nabs the star player doesn't get the supplemental pick to replace the talent lost. It's just no longer worth it.
Buster Olney wrote a great article about how this is playing out this off-season (I'd link but it's behind a paywall and too long to copy and paste). There is no coincidence that some mid-level talent, but not great players, are stuck in limbo at the moment because of this new rule. Give up a draft pick for Greinke or Hamilton? Sure. But Rafael Soriano, Swisher, LaRoche, Lohse, Bourn? Maybe not.
The real winners? Those that were traded midseason or not given a qualifying offer: Napoli, Dempster, Anibal Sanchez, Victorino...no draft pick is attached to them. And, no coincidence they've all signed.
It might also explain why LaRoche has sat for weeks on his 2-year offer from the Nats and why the O's haven't countered with more - that's a valuable draft pick.