My guess at this point would be that he gets convicted for having violated firearms laws, but not for murder. It's an interesting case, but the political climate surrounding it spans much more than just the shooting, and is (seen with international eyes and an attempt at staying impartial) completely bonkers.
He shouldn't have been there in the first place, and there shouldn't have been any incentive for anyone else to be either. The fact that there was a remotely plausible rationale for a vigilante policing force in the first place is just insane. That the police didn't roll up and say "go home, this is our job" is ridiculous. Then, of course, pouring fuel on the fire, the whole situation attracts a lot of people who want to commit violence - maybe including Rittenhouse himself. None of this should happen in a first-world country, and it's not something that will be solved with a murder trial. Regardless of its outcome.
There seem to be deep and persistent currents in American society that form the basis for events like these, and every honest assessment and candid dialouge attempting to fix them is a good thing. It might be off topic to a degree, but people getting life sentences willy-nilly is definitely part of the same web of causal relationships.