Millions of Windows Phone users are expected to download Windows 10 Preview for phones when it becomes available on more devices, so Microsoft is already considering an option that could be crucial for all insiders: releasing updates for RTM.

Gabriel Aul, head of the Windows Insider, confirmed in a tweet that "this is our intention," noting that such a feature could be implemented at some point in the future.
This is not surprising, however, as Microsoft is adopting a similar strategy for PCs, as it wants Windows Insiders to be able to upgrade to RTM easily, without requiring a fresh install.
In fact, Microsoft is working to make instant updates easier on all current versions of Windows, because users will be able to upgrade their systems to Windows 10 for free within the first year after its release.
Windows 7 and Windows 8.1 users will be offered Windows 10 at zero cost in the first 12 months after its release and the upgrade will be done through the built-in Windows Update.
In short, this is a pretty crucial feature for everyone, especially since it will require almost no user intervention and everything will be done quickly on all devices. Additionally, it reduces the risk of errors or other issues that could interrupt the installation process and therefore require further assistance.
