That's a private blockchain in hiding, since the relation of the NFT to the asset must be mediated by modifiable game code, at which point the dev could practically reassign ownership within their game world.
Private blockchains of course make no sense. But trying to find new ways to exploit gamers with microtransactions is always popular with some companies.
>I also like the idea of NFTs as game licenses.
Ultimately, the issue is that Xbox Live might want to shut down support, and could do that rather directly even with NFTs. If there was enough commercial pressure to not do that, this problem is trivial to solve with a permanent licence.
>I also like the idea of universal login using Ethereum addresses. I don’t want my identity to be owned by Microsoft, Google, Apple, of Facebook.
The various federated solutions achieve this without a blockchain. It's possible though to see blockchain 'winning' here - it won't be because of any technical advantage, but rather because it was made more available than other solutions.
I also like the idea of NFTs as game licenses. If the XBOX uses something like an Ethereum address as your XBOX account, it can verify what games you own by checking if you own the NFT that represents that game’s license. At that point, even if XBOX live shuts down support for XBOX 360 games in 20 years, my 360 will still be able to play any game I have the media for (ex: digital game copy on a USB drive).
I also like the idea of universal login using Ethereum addresses. I don’t want my identity to be owned by Microsoft, Google, Apple, of Facebook. I’d rather it be something I own (a public/private key pair) along with some known place to store attestations about who I am and what I can do (a blockchain). Those attestations could be stored off-chain, but that becomes difficult for users to maintain and program.