A namespace can be thought of as a rental dispenser with a templated set of parameters that allow the NFTs to be programmatically minted and rented on demand. Similar in ways to the Metaplex candy-machine, this works by minting the NFT and subsequently wrapping it in a token manager of the configured parameters. When it is returned to the namespace, it can be rented again by a new user.
In renting a username from a given namespace, you may be renting the right to play a game, access a service, or participate in a DAO. The username comes in the form of a managed NFT that sits in your wallet for the duration of the rental.
Holding a rented, managed NFT from a namespace that has previously verified your identity can allow you to assert proven ownership of something within that namespace.
A namespace can be setup to offer subscription-based access to gated content. When a user attempts to access the content, the provider can trivially check for ownership of the NFT.
Keys / Tickets
A namespace could represent a room in a hotel for which temporary access could be rented out. The rented key could also have have a usage-based expiration and be used as a ticket to an event.
Badges / Certificates
A namespace could be setup to rent out badges or certifications to a specific set of users. A user could be approved by the namespace and subsequently claim their badge that could be verified as issued and managed by that namespace.