I question the Democrats' ability to keep enthusiasm high for another 11 months. I doubt it can remain at the levels immediately post Trump, especially if Mueller clears Trump and Congress passes infrastructure spending.
lol.
If Trump was somehow "cleared" it would raise enthusiasm if anything. Hillary was cleared from every accusation thrown at her. Emails? cleared. Benghazi? cleared. That didn't effect GOP enthusiasm for hating her. The only difference is that Trump is guilty and won't be cleared in the first place.