My end-game prediction:
1. Mueller secures clear evidence connecting Trump to criminal activity. There will be 2 categories: 1) financial crimes including fraud, 2) severe ethics violations and conduct that could be construed as collusive and even treasonous
2. Closed door negotiations will result in 2) being qualified as "probable" in order to prevent a crisis. Mueller will release the findings to Congress and step to the side
3. Republicans will appear reluctant (at least in public) to agree to impeaching Trump, no matter how damming the evidence> From there it can go in two directions:
4.a. If enough Democrats win this fall he will be impeached. The country will get over it despite revolution cries from the likes of Gary
4.b. If Republicans still control Congress they will drag it along and refuse with Trump losing bigly in 2020 or deciding not to run at all
IMO, 4.b. is the better outcome for Democrats. This will inflict more division and pain on the GOP and they will really go out like a flame in 2020. Sure, impeaching him now would be great, but it's probably less strategic for the Dems.