Although there are still updates to BlackBerry 10.2.1 being released, it's no secret that BlackBerry 10.3 is well on its way. The developer OS has been released, the developer tools have all been updated and BlackBerry has slowly been offering everyone quick glimpses of what's next for BlackBerry 10. There have even been a few leaks of the upcoming OS, and while there is still plenty of time to make changes, it is likely that the leaks represent the final product quite well. BlackBerry 10.3 is slated to arrive with the BlackBerry Passport in September and after that, BlackBerry 10.3.1 will be released to previous BlackBerry 10 devices such as the BlackBerry Q5, Q10, Z10 and Z30.
While some folks aren't entirely happy with having to wait a bit longer to get their hands on 10.3, it is important to clarify that everybody will get 10.3. You'll just have to wait a little bit longer for an official release. For the truly impatient, there will probably be leaked versions also.
As mentioned, there are a few leaked OS versions in the wild. These are works in progress, with varying states of functionality. I use 10.3.0.296 as my daily driver even though it has some issues, but your mileage may vary. Use caution and realize you're riding the bleeding edge. Don't be upset if things don't work perfectly.