This isn't really a serious idea, but I thought it might be a fun discussion to have.
In all MMORPGs that I'm aware of, a clause exists in the end user license agreement that outlines the ownership of in-game items and characters. This got me thinking... because in D&D, or any tabletop game for that matter, it's completely up to the game master to determine if a character or their equipment can be used from another game. That character and its equipment are in complete ownership of the player. So, wouldn't it be interesting if that same level of ownership for characters and items in an MMORPG could also be moved down to the player?
This would technically be possible using blockchain. A blockchain armory could potentially act as a self-owned wallet of public and private keys for digitally owned characters and items. When a game requests access to that armory, the player can choose which characters and items the game would have public and private keys for. The game can then determine the ownership and origin of the character or items, allowing the game to selectively load those assets depending on their validity (origin, age, etc).
So for example, let's say you have a Conquer Online private server named Flux. In Flux, you get a trojan character to level 120 and obtain a super quality sword and an elite poison dagger (the server specializes in poison/dmg over time effects). Let's also say you level a water tao to level 110 and obtain a Dragonball from promotion. Now, you want to play on a new server called Beast that specializes in combat with pets and has lower leveling rates. They might look at your armory and approve of your trojan to a level cap and approve your super quality sword, but exclude your dagger since the server isn't balanced for those specialized items. Additionally, they might look at your water tao and approve all levels and the dragonball, but only allow one instance of that type of character to be transferred.
It of course opens up a can of worms for possible exploitation and such if not moderated correctly, but I thought it was still an interesting concept to explore. Cheers.
You explained how NFTs work pretty well. It's expensive unless you do this on TRON or ETH2, transfers are expensive right now but you're describing the future. Nice idea, some games implement this for avatar NFTs already only to enable trading of unique designed characters. Voxies is a current one, you could check this out for some inspiration https://voxiesnft.medium.com/voxel-tokens-fae1ad9a2b2c