Agreed on more workloads going to third party SaaS.

That might obviate a service like this, or else enterprises will want a service like the to broker auth and monitor access to their SaaS as well.

There are CASB (cloud access security broker) products now that do the monitoring and reporting aspect, though AFAIK don't participate in auth.

Almost certainly not because there's usually _something_ inside the corporation and so you then get the need for unified authentication management (e.g. Okta) and some way to access the internal app.