Edit: I don't accept a solution where I just have to hope that they will do something that enables me to play my games once the authentication servers have been decomissioned.
If I buy something, I want to know upfront what they will do, and it has to be guaranteed, not just a PR statement.
It has to be part of the TOS and I should be able to hold them accountable if they do not deliver.
And how is it a bad business decision to ensure that a customer can use his collection even if all auth/DRM servers are decomissioned?
This is the "bad business decision" that was made for every single big mainstream console since the invention of video games, and it seems obvious to me that the customer demands this, and MS understood it.