Tim Kring is angling to get Fuller back on Heroes. If PD has to go, at least Heroes can benefit. That show really lost something after S1 when Fuller left. Basically they need a producer who can handle characterization well and handle drama convincingly and coherently; the current crew are botching characters left and right, and are blowing serious chances for big drama. It's too bad because they really have all the right elements, they just don't seem to know what to do with them.
One thing I've seen in the comments about Heroes is that people are actually missing dramatic elements that I think the writers intend us to grasp, without which the characters start to unravel; they just aren't hammering things home like you need to do in TV. PD never had any problems with coherent, well-paced, well-put-together storytelling or disciplined characterization that never goes off the rails.
Some shows can survive by their fingernails but honestly, I don't think PD is one of them. The demographics are lousy, and ABC isn't totally desperate. Now if PD were on NBC, maybe...