Licensing Reports for guests in Azure B2B

Great to see Azure B2B reach GA! 

After reading about the licensing restrictions discussed here (https://docs.microsoft.com/en-us/azure/active-directory/active-directory-b2b-licensing), I was curious about the bullet point under "Additional licensing details" that states "There will be automatic calculation and reporting."

Is there any further information about how this will work? Is there any estimate when this will be available?

We are planning to utilize Azure B2B pretty heavily but need to have pretty clear visibility into how many licenes we need. We generally don't know if our partners are using Azure AD and certainly don't know what tier of functiality (Free, Basic, etc.) they use.

What if a large partner organization suddenly reduces their AAD tier and we don't have enough licences to cover the level of access we are granting guests (such as MFA)?