The Mueller report is a means to drive the impeachment narrative, the actual content is irrelevant, short of proven collusion, it's the mere existence of it and the last 18 months of media spin which matters.
If there is evidence of genuine collusion then the relevant material will be released as part of the judicial process. If there is no evidence of such, as seems likely, then the entire thing will have been written in a way to imply that there was undoubtedly collusion but it just can't be proved. There report will then be leaked.
The cosy deal to keep Cohen out of jail until his testimony can be utilised is another impeachment prop.
Nancy wants one, Nancy will get one.
Whether it shoots the Dems in the foot will have to wait until 2020.