Oh, grow a pair and announce your primary challenge already!
This seems like a weird reaction, given that it's only 2018. This isn't a parliamentary system, so Kasich can't force Trump out now, two years before the election. Trump's term ends in more than two years whether Kasich announces now or six months from now.
It's just annoying to hear him go on and on about this but then just sit back and do nothing.
"Trump is not the GOP."
"So does that mean you're going to run for President, become a large figure who opposes Trump, and push voters in your direction?"
"I have no plans yet."