Personally, I think the outcome of Manafort's trial will have a big impact on Mueller's investigation. The assumption is that this is the current highest-profile person in the indictments and prosecutors would/should have a slamdunk case with a preponderance of evidence.
- If he's found not guilty (without rampant suspicion/accusation someone rigged it), I suspect Mueller will take a lot of heat for not producing more with his investigation.
- if found guilty, I suspect Trump will come at Mueller hard and directly to cut off the investigation to stop any more progress that could lead to Trump himself or those close to him being indicted.
even if convicted, I suspect Manafort is not going to flip on Trump. Probably the one person they won't get to flip.