I think as long as voters realize that Trump believes in Trump and Trump alone, they'll be fine.
Romney's tantrum only reinforced Trump supporters, a lot of whom have openly stated that they know exactly who he is (not conservative, shifts on the issues, will do or say whatever to get elected).
But, they don't care.
Trump supporters want someone who will blow up the 'establishment', no matter the cost or ramifications.
I imagine Trump supporters won't mind at all when he pirouettes like a ballet dancer in the general election, because it's not facts or policies that are driving his support.
We might be witnessing the destruction of the 'Republican Party' as we know it.
For decades, the GOP has trotted out issues like abortion and guns to mobilize their base, and the base is finally realizing they're getting nothing out of it. On balance, aside from the seriously outlandish statements Trump makes (global warming is a Chinese plot, birther-ism, Mexican-rapists) most of what Trump is saying is correct, i.e.:
Politicians are bought and sold (elections aren't an exercise in Democracy, they're an auction).
Free trade is a scam that hurts American workers and only benefits corporations.
The tax system is FUBAR.
ETC.
It's very difficult to say he's wrong about these things - in fact, he's correct.
He's wrong about a lot of things, but those things don't matter much, in terms of this election cycle.
The GOP is reaping exactly what they've sown for all these years, and now they're losing their minds.
Very interesting election cycle!