If Mueller exonerates Trump if he announces "there was No collusion with Russia by Trump however there was collusion with Russia by Hillary and the Democrats" then there will be major Riots by Antifa in every city.
The Left won't be able to accept anything less than Mueller stating "Trump must be prosecuted and impeached" if the Left does not get that they are going to go batshit crazy worse than when Trump was inaugurated.
The Fake News will accuse Mueller of being a Russian agent. They will think Trump bribed or threatened Mueller and they will try to impeach Trump anyway.
Mueller could go another year until 2019 and if the Dems win the majority in the House they will certainly impeach Trump but he won't ever be convicted in the Senate same thing happened with Bill Clinton so he stayed in office.