*Technically* the investigation was about whether Russia intervened in the election, with no suggestion that Trump himself was invovled. But it pretty quickly ballooned out to be about collusion between the Trump team and Russia. I don't know if they've yet announced that Trump himself is under investigation, but like. He is. The writing is on the wall.
Its become pretty clear (since Manafort's arrest, arguably long before that) that Trump's inner circle from the caimpaign is going down from this. If any of you have been following the NJ bridge scandal, Chris Chrstie's inner circle was found guilty and at least two members served (are serving?) jail time. But apparently all of Chris Christie's advisors "acted independently and without his knowledge" to do this thing that was his personal grudge. So I guess they couldn't prove anything. Mueller's investigation seems increasingly a toss up between that kind of outcome, or another. In fact I see 3 outcomes for this.
1. Trump's (old) inner circle and at least one of his family members goes down for this, Trump ends up with an understaffed WH but otherwise fine.
2. Trump is impeached or resigns but faces no criminal charges.
3. Trump becomes the first president to face serious criminal charges other than impeachment.
IIRC 3 former campaign staffers have already pleaded guilty and we know they got leniency in exchange for dirt on more people. So there's no outcome for Trump here that's better than number 1. I guess maybe he could find some way to shield Trump Jr. from legal consequences, but I doubt it. Some people are beyond saving.