How the fukk will gamepass kill the xbox? You sound simple
For the most part, to play Playstation games and IPs you MUST own a Playstation. With GamePass lots of MS's IP go to that and PC as well. And with gaming PC sales on the rise and X-Box's last gen with dismal numbers, many of the potential customers for an XBox will already have PCs.
So if you have half your consumers on arguably a better platform already, you are giving them all the same games, what insentive is there for people to buy your (no longer) proprietary system?
If GamePass continues to grow and eventually becomes the Netflix of gaming...no there will be no reasons for them to pour hundreds of millions into hardware development, advertising and marketing.