Nobody knows when we'll actually see a Skyrim sequel, so until then here's this glorious mashup of Skyrim and Oblivion instead.
It's a mod called Skyblivion, and it's led by the TESRenewal group. The volunteers responsible have been working on the project for almost six years, with the project growing to work with Skyrim: Special Edition.
As described on the official website, the idea for Skyblivion is to port the entirety of Cyrodiil into Skyrim and Skyrim: Special Edition. The mod will be free to download forever, although users will need to own both Skyrim, Oblivion, and all DLC for both games for the installer to work.
The team published a new video recently, showcasing some the improved textures, models, custom weapons and environments users can expect. There's a new soundtrack as well, which you can hear if you listen closely.
The team also livestreamed an older build of the mod just before the New Year, illustrating the planned scope and scale. You can watch the livestream below, but the gameplay doesn't kick off proper until about 26 minutes in.