We will have to hear from Mueller himself but after reading the infamous letter and listening to Barr’s testimony there doesn’t seem to be much there there.
In essence the special council wrote a letter criticizing Barr’s brevity regarding the ins and outs of the full 440 page report during his original press release of the findings. The “why” certain conclusions were drawn by the special council and lack of charges were under represented, however the “what” as it relates to what their conclusions were is not in question. Mueller might perhaps take the Hill tomorrow and drop bombshell after bombshell of never before seen incriminating evidence but it is not likely.
It is more likely the heavily partisan committee is seeking some redemption from a media who has either painted them Trump advocates, too easy or just simply incompetent. In other words the only positive commentary they’ve received have come from Fox News and other sketchy conservative blogs etc.
Expect Mueller to outline a very carefully threaded needle as he weaves in and out of both political party’s need for him to side with as he pretty much says nothing more than what we already know.
Trump didn’t collude with the Russians and obstruction of justice is a subjective crime often times left up to the prosecuting officials. A recent and quite hideous example of that principle would be none other than the obstruction of justice clearly exhibited by Hillary Clinton. Far more evidence existed that she obstructed justice than that of Trump or his campaign and her lawyers were never exhorted under threat of life in prison in order to gain damning evidence.
Perhaps that needs to change.