With the Windows 10 November Update (Threshold 2) finished and released to the public, Microsoft has turned their full attention over to Redstone, the next major update for Windows 10 slated for release in 2016. Much like the original Windows 10 Insider Program and Threshold 2 Insider Program, Microsoft will be expecting Insiders to help test out Redstone too, and it appears Microsoft has started preparations to begin that process.
I have heard via various sources that Microsoft really wants to get a Redstone build out to Insiders before the end of 2015, meaning it could be just a few short weeks before Insiders are back running pre-release software. To support this claim, it appears Microsoft has started preparing Insider machines with the correct branch and ring data for receiving Redstone builds.
— Gabriel Aul (@GabeAul) November 19, 2015
You can check yourself by navigating to HKLM>Software>Microsoft>WindowsSelfHost>Applicability and looking for the BranchName DWORD value in Regedit, it should say rs1_release which is where Redstone builds will be distributed to Insiders.
Although Microsoft is trying to get a Redstone build out before the years end, whether they achieve that goal remains to be seen. If Microsoft fail to get a Redstone build out before the years end, they will definitely be pushing one out in the new year for Insiders to begin testing. Right now, Microsoft is focused on the rollout of 10586 publicly, which explains why the company is yet to make an official announcement about any future Insider builds. Gabe says he will be writing a blog post “before too long” about upcoming builds, so stay tuned for that.