Windows 10 hasn't been released yet and already Microsoft apparently is talking about the next major update.
"Redstone will be delivered automatically to Windows 10 users as part of their regular, every-month-or-so updates."
"Redstone also will be the vehicle for Windows core features that aren't going to make the cut in time to be included in Windows 10 this year."
According to Mary Jo Foley's sources: "My sources say the Windows Insiders program will continue throughout the Threshold/Redstone development/delivery/deployment timeframe, meaning Microsoft will continue to provide early test builds of not just the monthly updates, but the larger updates to Windows 10, too, into next year, and possibly beyond."
My view and not Mary Jo's view on this is as follows: This continuous series of betas available to Insiders could be a very big mistake as all too often users install a beta on top of a solid operating system and the result can be a disaster.