Based on the sheer number of indictments, the longstanding (and busy!) grand jury and the size and complexity of Mueller's team I'm pretty confident that he's going to uncover an absolute hoard of illicit and illegal behavior by multiple persons.
Some of the allegations contained in the Steele Dossier have already been verified by the Paradise Papers, the Panama Papers, and the Bahamas Leaks. They revealed that there is definitely a coordinated international white collar crime system in which state-assets from countries controlled by dictators (Russia, Turkey, Saudi Arabia, etc) have been funneled to US citizens in violation of US banking sanctions, tax laws, and elections laws. Manafort has already pled guilty to being part of this system, accepting foreign government funds to sway US policy and influence the election, and folks like Carter Page seem not far behind. Some of them, like Roger Stone and wikileaks, appear to have facilitated this effort without being paid directly for it.
The internet has finally laid bare the types of global corruption that have probably been common since the 1800s, and we're only now getting a glimpse into how the world's richest and most powerful people pull the strings from behind the scenes. This is Dan Brown style conspiracy, except instead of the Catholic Church it's run-of-the-mill autocrats and their plutocrat friends that are swaying entire nations into things like Brexit and Donald Trump. The "Illuminati" of popular mythology are sort of kind of a real thing, and we got to see them
high five in Argentina last month. Donald Trump desperately wants to be part of this club, so he's letting himself be a pawn in their game in hopes of joining their ranks in the future.
I don't think the Mueller report is going to be an easy read. It's definitely going to include some version of "Donald Trump's campaign coordinated illegal activities with foreign governments" but it's also going to back that up with an entire laundry list of specific instances of money changing hands in exchange for illegal activity, tax fraud and bank fraud and money laundering efforts to facilitate those payments, and the paper trails of people like Don Jr. and Jared Kushner explicitly trying to break the law by appealing to the existing global elite with promises of favorable treatment by the US government.
The problem with upsetting the existing global power structure is that I don't think the US Justice Department is really prepared to handle the prosecutions of people like Putin and MbS. Whether or not these people have broken US laws, there is an issue of jurisdiction when it comes to guys so powerful that they routinely
murder their enemies and
get away with it. I think the best we can hope for is that Mueller puts a bunch of US citizens behind bars for their role, and then publicly exposes the crimes of people like the Saudis and the Russians who directed those crimes in the hopes of educating the American public about the importance of electing ethical leaders in the future.
What happens to Donald Trump after that is kind of a footnote. America has already lost this game, for now.