Update (July 28): A spokesperson said: “At this time, Microsoft does not have anything to share” regarding the future of the Server Insider program. Earlier this year, Microsoft announced a change in its servicing plans for Windows 10 Enterprise LTSC, whereby new versions of that product will only get five years of support total instead of 10 years. The next Windows 10 Enterprise LTSC release is due this fall, in conjunction with the Windows 10 21H2 release.  (Thanks to ghacks.net for the pointer to the blog post about Microsoft’s change in servicing plans for Windows Server.)