The good news is that according to Microsoft, users who wish to roll back to Windows Phone 8.1 after installing the Windows 10 technical update will be able to do so. This was confirmed by Microsoft’s Gabriel Aul who is the head of the Insider program. In response to a question from a user, Aul wrote, “Yes, we’ll have a recovery tool to roll back for all phones that are supported for the preview.”
As to the availability of the technical preview, Aul hinted that it could be released this week. Aul had previously suggested that a new video demonstrating Windows 10’s features would be released later this week, after which he teased that maybe Microsoft could release the video along with the build. We had heard an earlier rumor that suggested that the Windows 10 Technical Preview would be released on the 9th, but given that it’s already the 10th, it is safe to say that the rumor did not pan out.