There was probably nothing Sony could do

Wrong, Sony could issue full refunds to customers or ask WB the royalties back. Sony should had a clause in their contract with discovery that allowed them to host the video files indefinitely, if it was voided all the royalties to be refunded as a penalty fee.

When Google closed their digital magazine store, they let users download the PDF or to get a full refund.

Google again, closed stadia and everyone got a full refund even if all the devs were paid

When a game is delisted on Steam, Valve continues to host the files for previous customers.

But here no, they already got the money, they know that console users are used to just STFU, they saw that they can save a lot of money by deleting hundreds of TB of video content, and seized the opportunity

At least have the decency to do a partial refund where only the royalties paid to Discovery are kept. Or if not a money refund a store credit as goodwill. Or a prorated refund/store credit according to how many times it was viewed. Never viewed = full refund, viewed once, keep the price of a rental, and so on. Or force WB to transfer the license in another digital locker.

But no, nothing.

Had I purchased that video content just to see it disappear from my archive, I wouldn't ever trust them anymore for future purchases and exclusively resort to piracy. (Well I do it already but this is an example) It's a lose-lose situation for Sony and for WB. The rightholders do extensive campaigns "please pay for movies and show, don't steal them", then if someone believes them and *purchases" the video content, he is the one that will actually get something stolen