We had earlier reported about Windows 10 Redstone 4 coming as Version 1803. Now official slides confirm that Window 10 Version 1803 will be followed by Version 1809 & Version 1903. Which simply means that after the release of Window 10 Version 1803 in March, Microsoft plans to release next feature updates in September 2018 and March 2019.
It is not yet clear whether these two will be called Redstone 5 and Redstone 6 but if the existing naming is followed they will be named so.
This is however predictable and can be deduced. With Microsoft clarifying that with Windows 10 as Service we will see a new feature update every six month, it has become easy to guess version number for upcoming Windows 10 major updates. For example, version 1809 has “18” for the year and “09” for the month, signifying a planned release in the 9th month of 2018.
But it is always better to have some sort of official confirmation and the slides confirm that Microsoft plans to follow the six-month release plan.
As once can notice in the slides each feature update will be supported with updates for next 18 months after release.
Source: Microsoft