Not much will change about what we do know. Some of the people acted irresponsibly that day. Criminally so. Then again, you can take a snapshot of an event where someone is acting poorly and use that snapshot to sell a story.
For instance, Rodney King gets pulled over for acting poorly. High on drugs, resisting arrest. If you stopped the video or edited as such to take out the part where the four officers were beating the shit out of him...well, you are kind of missing a big part of the story.
There may be nothing in those 40,000 hours of tapes. Then again there may be things like police opening the doors and welcoming people into the Capitol who were later charged with parading. We might see police escalation against people who were caught in a crowd and not necessarily acting violently towards the officers. What we have now is the black and white version of events. Trumpers bad. Government heroes. How often is life that simplistic though? The government seems to be awfully intent on controlling the evidence and therefore the narrative around that day. That leads me to believe there is probably going to be some things inconvenient to that narrative in those videos. That wouldn't change the fact that some portion of the protestors that day turned into rioters, but it may change our views on the various involved government agencies and their potential culpability that day.
At the end of the day, we shouldn't fear sunlight. Who cares if Tucker gets to look through the tapes and air what he finds? There shouldn't be anything left to find after the completely impartial investigation and hearings performed by Congress. Those are our tapes, that is our building, and the government is our employees. If all the tapes show is Trumpers acting bad, then the release of the tapes should put the arguments about that day mostly to rest.