JDS knows he needs to face at least one other opponent before getting his rematch, just as Cain did. The problem is, there's literally no one else in the division that JDS doesn't beat the tar out of (including Overeem, imo). I'd like to see JDS tested against another top wrestler, but there really aren't any who even come close to Cain's level of wrestling. It's pretty clear that JDS and Cain are 'the guys' when it comes to HW, especially if Cormier does go down to LHW.
Cain beats JDS. JDS beats Cain. And I don't think anyone else touches either man for some time. That might become problematic for one of the two down the line. I suppose Overeem could shake things up, though who knows what he'll look like without his magic beans. He was already slow... can't imagine him off the juice.