The only thing we know for sure is after the Presidential election, those in the losing party will start blaming each other for blowing it. Here's a preview.
If Trump loses, which seems likely, the GOP will be finger-pointing in every direction. We were too conservative. We weren't conservative enough. We shouldn't have moved in the Trump direction. We have to go all in with Trump's populism in the future. We shouldn't have chosen someone with no experience who's such a loose cannon. We blame the media. And so on.
The fight over the party's direction will likely be strongest if Trump loses in a close race, since then his supporters can say the message worked, but it came in the wrong package--and also he didn't get the backing of the Establishment of the party. If he gets walloped, perhaps it'll scare or shock the GOP into going back to more conventional candidates.
If Hillary loses, it's hard to say how the Dems will react. Will they say she just wasn't a good candidate? Parties always do when they lose, but who did they have who was any better? For that matter, will they blame James Comey, WikiLeaks and overblown scandals?
The main question is will they convince themselves that someone more radical (but magnetic) like a Bernie Sanders or Elizabeth Warren, is needed, or will they say it's time to return to the third-way politics represented by Bill Clinton (that Hillary moved away from this election). In 1992, it appeared the Democrats were forced into moderation (as they see it) after being out of the White House for 20 out of 24 years. But now that they've seen they can win these days with someone a lot more left, and as a party find Bernie Sanders far more appealing than, say, Jim Webb, there may be no going back, at least not for a few more election cycles.