Poser 13.1 is now available, and includes the new Mac version alongside the Windows version. It’s a free update for Poser 13 licence holders. Lots of rendering quality improvements for SuperFly (Poser’s version of the latest Blender Cycles). See the linked page for the full list.
No mention of changes to the Windows OS spec, so you should be able to run it back to Windows 7 (though without access to store-purchased third-party scripts on Windows , and likely with no helpdesk support).
No changes to PostFX on Windows, to OIDN de-noising, or to Poser’s unique abilities with real-time comic-book line-art, Firefly line-art, and Sketch rendering.
The current released version is 13.1.449.