I think he has tremendous growth potential.
He's arguably the most experienced 2016 candidate as a big-state Governor who served in the congressional leadership (six years as House Budget committee chairman.) And by 2016 candidates, I'm including Hillary.
He's been a cable TV host, so I'm guessing he can do pretty well on the stump, and handle himself well on the media.
He just won reelection in a landslide in a state Republicans need to flip.
There isn't significant opposition to him, in the sense that there aren't that many in the party who would be outraged if he got the nomination. He's got more gravitas than Walker, and less baggage than Jeb.
It's possible there won't be an opening for Kasich if Jeb rebounds, Walker handles himself well, or Romney decides to run. But he definitely has a shot.
I think it's arguable that Kasich is the "best qualified" candidate the GOP has, especially if you throw the ability to beat the Democrats into the mix.
Kasich, by the way, has been beating Democrats from day one. In 1982, a bad Republican year, he upset Rep. Bob Shamansky (D-OH) in a Columbus-based district. Shamansky had been elected in the 1980 Reagan year, so he wasn't a slouch.
From an electability plane, Kasich looks better by the day. His qualifications reinforce his electability, and not the other way around. These are good things in finding a winning Presidential candidate.