In all honesty, I think the Mueller report barely moves the needle no matter what it actually says.
The idea of Trump being “exonerated” is foreign to me. There is plenty in the public record that is damning enough to at least suggest the idea that he was acting inappropriately with respect to Russia (and other countries) whether or not he technically committed a crime.
If the full report is not released, the argument will just shift to “what are they hiding?”
If the full report is released, I find it nigh impossible that there are not a number of details in it that paint an unflattering portrait of Trump and those in his campaign, and the argument will just shift to that.
In my view the report will likely actually contain very little new information as we largely know the broad strokes of the big picture. Trump was trying to develop Trump Tower Moscow during the election, and had a potential payout of millions of dollars stemming from that. Trump was trying to curry favor with Putin during the election possibly because of that. His campaign was willing to accept a meeting with Russian officials ostensibly to gather dirt on Hillary Clinton and in that meeting discussed lifting sanctions on Russia. His campaign manager was giving briefings to people connected to Russian intelligence about the campaign, including sharing polling data. Presumably Russian intelligence was using that information to enhance their disinformation campaign.
I think there’s arguments to be had about whether those are crimes, should be crimes, and/or whether Mueller is too cautious in choosing to prosecute. But I don’t think the report will actually contradict any of those facts. They are all basically from the Mueller indictments themselves.