I honestly have no certainty, other than to say that the Green and Libertarian party will be increasing in numbers, both. How much, how relative, it's totally unclear. It'd be a serious mistake to think that right-wing libertarians (largely Gen X'ers) will in line with the GOP and the left-wing libertarians/progressives/socialists will just fall in line line with the DNC... That would be a very optimistic outcome for Hillary. I seriously doubt that that solidarity in either party will happen in droves. At least a third of the Republican base fervently hates Trump and a third of the Democratic base fervently hates Hillary. I heard a commentator state "It's not unreasonable to think that either of them, after a protracted 7 month negative campaigns, could enter the White House with approvals ratings in single digits." I tend to suspect that's a rather reasonable possibility. Independents hate Hillary and they hate Trump, both alienated at least a third of their base, and both are about to be exposed as massive corporate shills (Trump is certainly about to take on loads and loads of debt to corporations, Wall Street, etc to get the money he needs to take on Hillary, and he's already said so).
I foresee a drifting of party's bases or else an emergence of a third party. We've reached that point, I think, when finally last year more than 50% of voters are registered as Independents, and the only people who actually get serious, grassroots supports are (morally third-party) people like Sanders and Trump, and previously Paul.