I have serious doubts about Congress' ability to bring impeachment to the logical conclusion of removing Trump from office. Here's the most likely scenario--the House waits for final Mueller report and their own public subpoenas and Judiciary hearings to conclude. My guess is sometime mid- to late-2019. At that point, House votes to impeach, and then impeachment goes to the Senate for execution. Meanwhile, Trump and his staunchest allies rail against the "political witch hunt" and slander these reps the same way they did FBI, the intelligence community, etc.
Once impeachment goes to the Senate, McConnell and Pence do everything in their power to stop it going through. Mitch will form an "impeachment trial committee" that will review the evidence and call witnesses behind closed doors, twiddle their thumbs, and avoid dragging a public impeachment trial into an election year at all costs. Bottom-line, impeachment will never come to the full Senate for a vote before the next presidential election. Trump will likely not seek reelection on advice of the GOP establishment, and would likely have primary challengers anyway. If Pence can keep his hands clean of all the Russia stuff, obstruction stuff and GOP campaign finance violations stuff, then he'll probably emerge as an early front-runner vowing to continue "Trump's radical agenda" without Trump. If Republicans somehow manage a win (Electoral College + voter suppression) I'm sure Trump will quickly be diagnosed with some medical ailment and he (along with family?) will be pardoned for any crimes committed for medical mercy reasons.