A) I think that Trump could win in 2020. He is really, really good at campaigning. Also, the Dems will be in a bitter campaign fight and will likely choose someone of the left. They could easily beat Trump with someone from the center-left.
B) The House will spend January 2019 through the 2020 election with over a hundred investigations of Trump, his campaign, his transition, his companies, his family and his cabinet. Impeachment will be a side issue, and won't matter much.
C) For now, I presume that the Democrats will have a majority in the House and the Republicans the majority in the Senate.
D) Trump will get lots "done" in the next year and a half. Of course, almost none of this will be issues that require legislation. Lots of court justices will be appointed. Trade deals will be made, The tariff fights will continue. The battle against immigrants and refugees will continue. Deregulation will continue.
E) There will be fights at least a couple times a year when debt limit increases or appropriations are needed. This is when compromises can happen (probably on the wall and immigration). There will be a government shut down or two or more.
F) After another year, Trump will decide whether it is worth running again, or whether he wants to spend his time protecting his family and fortunes. Much MAY depend on other Republicans. Trump can force his nomination, but not their support. Republicans may understand that they can indeed afford to lose the presidency (for 4 years) as long as they control the Senate. By January 2021, their Court victories will seal the fate of the judiciary (SCOTUS and lower courts) for many decades. The change in the tax code can't be changed without the Senate. Republicans won't get anything meaningful in legislation with Trump as president and a Democratic House. As an aside, the Republicans could easily lose their Senate majority in 2020 if Trump heads he ticket.
G) Democrats would find it difficult to beat Hailey-Kasick in 2020 or 2024, or even Rubio with one of these two. The open secret is that Hispanics are likely to be Republicans in lots of jurisdictions.