Ability to use Modern Auth on outbound SMTP. Although MS are not forcing this yet if the enterprise is moving to this then support should be available.
This starts October 1st, 2022:
"In September 2021, we announced that effective October 1, 2022, we will begin disabling Basic authentication for Outlook, EWS, RPS, POP, IMAP, and EAS protocols in Exchange Online."https://learn.microsoft.com/en-us/exchange/clients-and-mobile-in-exchange-online/deprecation-of-basic-authentication-exchange-online
No that is for Modern Auth Inbound only, currently MS are not doing anything Outbound on SMTP but have introduced the ability to do Modern Auth on SMTP as well if you so desire. Is it this which this Feature Request is about.
If you are still not ready of Modern Auth you can apply for an extra 3 months of Basic Auth on your Tenant - see One Last Chance to Pause the Great Exchange Online Basic Authentication Shutoff