I know this is an odd thought, but we learn through the series that those who are sealed in the reapers belly are essentially doomed to toil and never find peace in the next life, however the only soul we know are sealed in there are the 1-4th Hokage.

Now, I know what people will say "what about Orochimaru and half of the 9 tails" I guess we should draw the lines of conscious soul vs. unconscious soul. I am wondering whether this will be addressed or not, and what the "tribute" would be to release those souls trapped within the reapers belly.

Why bring this up now and what does it have to do with the current situation? we currently have a situation where Madara is out in the open and has resealed his soul into the sacrificed body of (probably Anko), with what we believe is no foreseeable end. So why is that important? it shows that the terms of a contract can be changed in different types of "forbidden jutsu" so it makes me wonder if the reaper contract could also be changed to release those who are trapped to be released.

I haven't quite worked out the details of how, but I have a feeling it will have something to do with the Rinnegan. I am not saying that the souls of those trapped will be brought back to life, but more freed to find peace, as well as Kurama getting what chakra was lost (perhaps we see this as the final powerful before the last battle).