I'm not overly optimistic about this report. I think the best case scenario will be that the report will state there is not evidence that the Patriots did anything wrong, but there will be enough vague references* and buzzwords in there ("concerns" "irregularities" "wasn't able to speak with" "footage wasn't available") that the team will look guilty.
Some people have said this all along, but with the stance the Patriots took, that science was on their side, and the speculation that the Colts or the league were being investigated, I thought we would see an exoneration and exposure of the rats in the system. The slap on the wrist that the Jets just received for tampering has changed my mind: We're not going to see anything that benefits the Patriots.
The league office isn't going to admit that they ran a sting on a team or that someone intentionally leaked damaging information about that team to maximize the distraction and bad publicity. They're not going to sully a 'feel good' story like Chuck Pagano or the next golden boy, Andrew Luck, by looking into the motives and actions of the Colts. Even the scientific information could be marginalized by the report saying "This can explain the change in air pressure, but we're just not sure if any other external forces were at work." People will focus on the last part of that sentence rather than the first.
In the bigger picture, if the report shows there were shenanigans going on with Kensil and Grigson and this was an attempt to smear the Patriots, the league will look bad. People will question the league's integrity. Or the report could show that there's something fishy going on in New England, but they just couldn't prove anything. People will just question the Patriots then (which is what they've already been doing) and forget everything else. I'll be happy to be wrong, but I think this is what we're headed for.
*An example of this from 2008 - Goodell says the Patriots did not gain a competitive advantage from taping signals, but never expands on that. That left most people wondering why such a big deal was made of the situation and the punishment was so great for a non-advantage and took it as an attempt to downplay the whole thing. All he had to do was say "The cameraman had the tape with him the entire game and no one else saw it until later. Sometimes days later." That would be an accurate statement, but Goodell never said it.