While this news is making huge ripples among the left Windows 10 Mobile community, but this was pretty much obvious the way it has been going for Windows 10 Mobile since a year now. The platform is officially dead after multiple, but indirect confirmation from Satya Nadella, Joe Belfiore, and many others. Joe in fact clearly said that there will be no new features that would be rolled out for the existing customer base, and they can only look forward to security patches and maybe enterprise features if that gets to pass through.
That said, the Insiders became pointless that very moment. There is nothing to test, and its a cost for a company to keep running insiders program with no future plans. In fact, the last major update that came was with Creators Update. RS 3 or the Fall Creators Update did not bring any major features to the platform.
The confirmation came from Brandon LeBlanc, Senior Program Manager, Microsoft on the Windows Insider Program Team in WDG, and Jason, who is Sr. PM and Chief Taco Hat Officer on the WindowsInsider Engineering team at Microsoft. He said “Plans Change”, even there had been multiple confirmations from Brandon before that this will go on. I don’t blame either of them, it was pointless anyway.
So if you are still running the Insiders build, I would suggest you leave the program as there is no point, and you will only feel sorry for it. You will receive the security updates, and bug fixes if that matters.