The first indictments in the Watergate Scandal were made on Sept 15, 1972 when E Howard Hunt, G Gordon Liddy and the other Watergate "burglers" were indicted by a Federal Grand Jury.
But it wasn't until July 30, 1974 until the House Judiciary Committee drafted and approved the Articles of Impeachment against Nixon, with Nixon resigning on August 8, 1974.
In the intervening 22+ months a number of others connected with the Nixon campaign or administration were indicted, convicted and investigated.
Why are you presuming that just 9 months in, that this was somehow the ultimate action that will happen in this investigation? Just like with Watergate, it's going to take some time to either exonerate or indict anyone else.
Technology and information differences between 1972 and 2017 would hopefully allow this to move slightly faster. If we are still talking about Mueller investigating Trump in 2019 with nothing more than what's come out so far, then I'll know for a fact this was nothing more than a witch hunt hoping to find something to restore the political establishment back to its perch.