Is it that expensive to just keep a database of codes that can be redeemed for people who haven’t migrated yet? Like humble bundle keeping track of what you buy? Or even lemmy with comments linked to users?
A proper corporate database with the security it needs and the amount of people accessing it (remember how many people bought Minecraft) yes it would be expensive to have multiple databases doing the same thing.
No it wouldn’t, millions of people bought it but the vast majority migrated, even if there were still millions of people to migrate this wouldn’t get hit very hard because people would not migrate all in one go, so any simple master+slave database system would work, even an SQLite is capable of handling this volume. The total cost of this would be less than $100 per year if they wanted to outsource everything (which is essentially nothing for Microsoft), if they used any of their existing servers for it the coat would be a lot less possibly very close to 0.
They could handle it through support. Remove the automated process and do an email verification check and support could manually migrate the license.
I totally understand Microsoft’s desire to remove obsolete services like account transitions, but they should still have a mechanism for resurrecting old accounts if you can prove you are the original account holder.