Apple rolled out developer beta 4 for iOS 10.3.3 on Thursday so the official release can’t be too far off.
It’s seen as a maintenance release, and any remaining iOS 10.3.x releases are likely to be security-related in the ramp-up to a Fall release for iOS 11.
The beta will bring new wallpapers to the 12-inch iPad Pro, along with minor bug fixes and security patches.
In addition to a new developer release of Sierra, Apple also seeded developer releases of iOS 10.3.3, watchOS 3.2.3, tvOS 10.2.2. All three releases are most likely going to be bug releases, and they come just one day after final versions of their predecessors.