It looks like the sign-in report is now becoming available to all customers, not just those with Azure Premium licenses - good news. Thanks for your patience.
Now to answer some more questions;
aspantel - we're not adding OAuth for EWS to Outlook.com. EWS is not being invested in any more.
Terry0820 - correct. Azure AD Sign-in shows sign ins to all apps, not just EXO. Thsi change only affects EXO.
Sankarasubramanian Parameswaran - POP3/IMAP - yes, CBAinPROD means Basic right now. If you push the reg key (which doesn't need to be done on Outlook 2016+) before you enable MA at the tenant level then all clients should switch once you do.
David Lowy - As the blog said, POP and IMAP are rolling out now, so not long. We have a change Azure need to make too, so we're also waiting for that before we announce it.