I don't know what running up in the minds of Xiaomi but their decision is killing me. Ever Since their New Mobile & Hyper OS showcase many have tried to migrate to use it, may be too many bootloader unlock request during the time was reason made them think that it would affect the sale of their latest mobile (u know the user experience before even releasing the phone worldwide...) May be that is the reason why they shutdown I guess... Just my Personal opinion.
But their decision is simply stopping me from moving to Lineage OS. But I suspect they may bring the service back after couple of months after their phone release.
Like disroot's service and user experience