all three have really low approval ratings:
Bobby Jindal 34% (down from 58, in 2010)
Rick Scott 33% (Lt. Gov't Resigned last week in a gambling scandal.)
Tom Corbett 33% and never was popular.
It's very early, but i dunno. All three have been trying to outsource public services and perhaps the people don't like it (Of course we thought the same with Walker and he survived).
On paper Corbett has a lot going against him (unconstitutional outsourcing of the lottery, the investigation into his involvement with the Sandusky case as well as his suit vs the NCAA) but he has history on his side. No incumbent has lost reelection since...i dont think ever, in PA, and he doesn't look to be facing any strong candidates at this point.