Nixon added that all Windows developers are still working on Windows 10 and that employees can talk freely about future updates because there's no secret update in the works coming next. It's all just Windows 10 and Nixon confirmed the future is "Windows as a service."
What this all means is still a bit murky but it seems like Microsoft is planning to ditch the version number as it plans to deliver a regular continuous stream of improvements and updates rather than big releases that arrive on much longer cycles like it did in the past.
With Windows 10, it's time to start thinking of Windows as something that won't see a big launch or major upgrade every few years anymore. Much like how Google's Chrome browser gets updated regularly with version numbers nobody really pays attention to, Microsoft's approach will likely result in a similar outcome. This is really the idea of Windows as a service, and the notion that Windows 10 could be the last major version of Windows. Microsoft could opt for Windows 11 or Windows 12 in future, but if people upgrade to Windows 10 and the regular updates do the trick then everyone will just settle for just "Windows" without even worrying about the version number.Source: The Verge