We have no idea if that will happen — or if there's really anything for Manafort to "flip" on. But that fact that Trump's campaign and now his White House find themselves in this position is, in part, due to that same attitude on display on election night. Trump has played fast and loose with pretty much everything, from his campaign to his administration. He has flouted both tradition and basic political safeguarding.
But that's also the kind of thing that can catch up with you over the long haul.
Manafort's overseas work and ties to pro-Russia political forces in Ukraine were really no secret. "We joke in Ukraine that it is a bad sign for Trump that he hired Manafort, because his client [Viktor] Yanukovych was ousted and fled to Russia, to the city of Rostov," Ukrainian political expert Oleg Kravchenko told Politifact in May 2016, shortly after Trump hired Manafort to steady his unwieldy campaign. "So Trump could also end up in Rostov. It is almost like an anecdote."
Manafort's overseas work eventually led to his ouster from the campaign and is at the heart of his current problems, but not before he had served for a five-month period spanning from the latter stages of the primaries to the early part of the general election campaign. He was at the meeting that Donald Trump Jr. set up with a Russian lawyer who we've come to find out discussed the topic beforehand with the Kremlin's equivalent of the attorney general.
Manafort was the kind of figure that any normal U.S. presidential campaign likely would have avoided. Whether Trump's campaign was unaware of these problematic ties or simply never bothered to vet Manafort (I'd wager both are possible), it's now proven to be a serious error of judgment. Whatever Manafort knows, he's now in the position of potentially using it to save himself.
This kind of error of judgment never irreparably harmed Trump during the campaign. And as Bannon believed, it arguably helped him by serving notice to everyone that he he wasn't your average politician. The more the media highlighted Trump's tendency to fly off the handle and stoke controversy, the more his supporters seemed to dig in and defend him.
But while that might have worked as a great political base strategy, it is far less ideal when the decisions you're making have real political and legal consequences. Trump has largely brought his Russia problems on himself, most notably by firing FBI Director James B. Comey. That paved the way for Deputy Attorney General Rod J. Rosenstein to appoint Mueller as special counsel — a move that removed this whole investigation, to some degree, from Trump's chain of command.
Now that Mueller has apparently penetrated one of those closest to Trump's political rise, we may see just how much much of a problem Trump created for himself.