It's a long story. For the 1st year or 2, we'll all have to watch with a certain level of embarrassment as Trump learns how Washington works, and figures out that you can't repeal Obamacare or build a wall by snapping your fingers at a few underlings. As we know from Trump's personality, this will be extraordinarily frustrating from him, and instead of trying to build coalitions and consensus, we'll likely have late-night twitter wars with members of Congress and other associated tantrums.
He'll also try to back up his tough talk on terrorism & ISIS with poorly thought-out military action, alienating our allies and diminishing America's reputation in the process. He'll lash out at the domestic Muslim community and create an "us vs. them" mentality, depriving us of valuable intel that could prevent attacks. Emboldened by having a leader who sees things "their way," bigots everywhere will increase vandalism and vigilante attacks against innocent Muslims and other minorities.
Women will have it rough. Trump has talked about getting Roe v. Wade struck down "immediately," and that's actually the one thing he'll probably be able to do (though not right away).
If people think the debt has increased badly under Obama, they ain't seen nothin' yet. Trump's huge tax cuts along with increased expenditures on things like the military do not add up, even according to conservative analysts. Far from reducing the debt, as promised, we'll see huge increases to what we have now. If by any chance he can repeal Obamacare, he has promised to just replace it with "universal healthcare" that the "government will pay for."
In the end, he'll abandon most of his promises, because he doesn't really care about them anyway, and work on his post-Presidency brand to try to maximize profits for himself. Democrats will regain control of Congress, and Trump will get an historically low # of electoral votes for a GOP candidate in 2020, changing the electoral map and making states like Texas battleground states. The GOP will have to reinvent itself and start the long process of trying to win back women & minorities, which could take decades.
