Frankly, I don't think anything will happen:

He'll fight any attempt at an interview every step of the way - probably for years.
Congress will do nothing that might hurt themselves. So even if there could be a successful impeachment, many will fear the backlash of the voters - who already follow the "deep state" narrative so the more evidence there is the more they believe it.
Democrats have a small window to have a candidate that stands for something before 2020 else the D man will be back and after another 4 years he'll be too old to bother standing trial.

Whether other members of the Clan start to feel the heat and then if we enter the murky world of "I'll pardon my lot, resign and get my own pardon on the way out" might be a possibility.