So, will the Neocons abandon the Republicans?
Neocons basically split off from the Democrats about 40 years back, over the issues of support for Israel and being more aggressive on the world stage. They never really cared much about social issues either way, and still don't.
They did care, however, about not being morons. They don't want an idiot starting WW3. And the anti-intellectualism of the Trump faction scares them. Noecons know they'd be up against wall themselves eventually. Trump backers don't trust anyone who can use 4-syllable words. Think of Pol Pot purging all the educated when he took over.
I don't see their leadership sitting it out. Neocons, above all, love influence, and you don't get that by doing nothing.
So, will they return to the Democrats? After all, Hillary is no pacifist. They'd have a chance to influence her. Or they might go full Quisling, and support Trump, in the hopes that sufficiently slavish devotion will save their skins.
In any case, peeling off just a slice of the Neocons will make for a Democratic rout.