Domain or subdomain based access is available today to Stores / Events and every page.
video link: https://www.screencast.com/t/K2kgFqCBM
If the user login into the saas website. we are redirected to a particular user subdomain store view page.
If the user does not create the subdomain, we are redirected to our saas store view page. This can happen in event as well and video auction