The idea is to run wordpress on cloud (Google Cloud, Amazon S3 or any private cloud) and use the multisite feature to have different domains.
It will allow users to register and choose the theme of their dream and they can go online by a single click!
Mostly the users who use wordpress for blogging won't need to download wordpress and host it separately. They will just need to register and choose the theme.
The only thing is, this will require a server with high capacity to store the huge amount of data.
Hope you will like it!
Thank you. :)