If the House votes to Impeach.....
a) The impeachment could make Democrats and Independents, and maybe some Republicans, more eager to vote him out of office
b) If Trump wins reelection, and the Democrats take control of the Senate as well as keeping control of the House, the Impeachment doesn't expire. The Senate can complete the Impeachment process, removing him from office.
Odds are good one of these scenarios will happen.