The next major feature update for Windows 10 is looking to be called the "April update", if an official page in Microsoft Edge is to be believed.
In a server-side update to the Microsoft Edge browser (via Windows Latest), Microsoft has updated the welcome page that greets users to the changes that have been made in the update. On this page, it makes reference to the "April update".
It is possible to access this welcome page directly in any browser on the MSN website here. This is a strong indicator that Microsoft is getting closer to pushing the next feature update to RTM, provided no blocking issues are found before rolling the update out to users.
This latest update has already experienced setbacks, with an original release date of April 10th, but bugs have caused the company to further push the update back, now coming towards the end of April.