If they use the blockchain as designed, there will be no central server to switch off - it’s just running in a bunch of basements. They rarely do, though.
The person who stated this a while ago deleted their comment so the reply may not have made sense:
The blockchain does not contain the digital assets. it is just a ledger saying who owns the assets.
If the place the blockchain ledger points to no longer exists, the ledger is useless.
Same with NFT’s, they are digital receipts that point to a web address, If the web address closes down, the NFT is useless.
For a real world analogy.
A deed (blockchain ledger) proves you own a house (digital asset stored on the game server). If the house burns down (game server is switched off), the deed still exists but it is useless as the asset it describes no longer does.
