Thank you for posting your query on Microsoft Q&A. From above description I could understand that you are looking for a timeline on Entra ID support for SAML Single log out via HTTP POST Binding.
As of now there is no ETA or roadmap available for this feature. However, please be informed that any recent changes are posted on What's new in Microsoft Entra ID? by our dev team, please be posted on this page for any updates.
Thanks,
Akshay Kaushik
Please "Accept the answer(Yes)" and "share your feedback ". This will help us and others in the community as well.