Microsoft is getting ready to make Windows 10 21H2 available to mainstream users. In an October 21 blog post, officials said users should get ready for the Windows 10 November 2021 Update, a k a Windows 10 21H2. (Rumors had pegged October as the rollout month for 21H2, but it looks like it will arrive in November instead.)
Microsoft is making the 21H2/November Update available to all Insider testers in the Release Preview Channel. To get it, Insiders on 21H1 or lower need to "seek" it by going to Settings > Update & Security > Windows Update and choose to download and install 21H2. If Insiders update to 21H2, they'll automatically get new servicing updates via Windows Update. Microsoft already made 21H2 available to Windows Insider Program for Business participants for validation on commercial PCs.
Windows 10 21H2 won't offer many new features. It will behave almost like a Cumulative Update, in terms of size and speed of deployment for those moving from 21H1 to it once it's available.
Microsoft officials have declined to say whether or not Microsoft plans to continue to make two feature updates per year for Windows 10 after 21H2. All they've said publicly is Microsoft will support Windows 10 until October 2025 with security updates and fixes.