If the suit is found in favor of UGM and enforced at full effect (not impossible, but Hachette v. Internet Archive was not either), then IA will be on the hook for the full $621 Million. You can guess how that ends.
But even if they don't enforce at full effect (and given Web Archive has been successfully used to provide evidence against UMG and Sony multiple times now, they have a pretty strong incentive to get it burned down), a sizable portion of the 400,000 recordings are from disks that quite literally broke down after capture. Those disks are the last copies of those recordings. Ever. Should UMG and Sony succeed, it is a very safe assumption, given they already confirmed they don't have those recordings (and based on that, don't want them), that those recordings immediately become lost media.