soon? like before luther's countdown?
I'll take a stab at a timeline:
In Watergate, it took almost 16 months from the appointment of the Special Prosecutor to Nixon's resignation. Things were slowed down a bit by Nixon's firing of the SP, of course.
Will Trump fire Mueller? I believe he will... he'll use whatever political cover he (or his lackeys like Nunes) can manufacture. This will slow the investigation down. But public sentiment against him will increase, and moderate republicans may fly the coop. Regardless a new Head of the Special Investigation will take over and continue.
But Trump will NEVER resign. Hell, he would start a war with Korea first to stop any attack on him. This will delay the process.
Democrats will certainly take majority of the House in November and perhaps the Senate. If the Special Investigation reports Obstruction of Justice before the end of this year (likely IMO), then the House will DEFINITELY impeach him this year. Beyond that, hard to say... the Senate's supermajority requirement is a HUGE hurdle to cross during the actually prosecution of impeachment. Too many variables to predict that, but all things being equal, an unlikely scenario.
Caveat: Mueller could attempt to actually indict the President which changes everything. No clue how that plays out other than Supreme Court followed by ugliness.
My gut tells me that Trump's evil goes beyond just obstruction. He is a fundamentally flawed human being much like Nixon. As such, I suspect worse charges forthcoming - most likely money laundering and conspiracy to rig the election. Either would be the stake in the heart of Donald.
There is a ZERO percent chance of Trump completing his 4 years in office. One way or another, karma will find him.