It's been in development almost as long as this website has been around, but the Tamriel Rebuilt mod for The Elder Scrolls 3: Morrowind is still in active development after all these years, and has even announced a new development roadmap.
The mod's ultimate goal is to start building out the rest of Tamriel to Morrowind's map, with hundreds of new quests and characters to flesh it out, adding hundreds of hours of new content to the classic game. According to the team behind the mod, they want to achieve what Morrowind was always supposed to be in the concept stage, namely an Elder Scrolls game that included the entirety of Tamriel, and not just one region.
It's taken them the best part of two decades, but they've achieved roughly "50%" of that goal, which puts the work ahead of them into perspective. That leads us nicely onto their roadmap, with the Velothi Mountains and the western edge of the continent up next, along with some new original locations to help bring things into check, known as the Roth Roryn badlands and the Armun Ashlands.
According to the developers, "the release area also contains our first major Hlaalu city—Andothren—which will be the main focus point for the more than 140 quests currently on track to being included in this release." The team are also planing to head East, with the Thirr Valley region also coming soon. "This area is home to a multitude of small to medium-sized Hlaalu trade towns and tanna plantations, all nestled between thick mushroom mangroves. The Redoran Waters March, almost entirely pushed out of the region by Hlaalu expansion, holds on to a precarious existence in the twin river fortress of Ald Iuval and Ald Marak. Overtly, the region is peaceful, but players may soon find themselves entangled in webs of vicious underworld rivalry."
Naturally, there's also some reworking of existing content being done too. The roadmap also includes lots of new screenshots to check out of the work in progress. You can even download and play the mod in its current state right now. Hopefully, we won't be waiting until 2041 for the finished product, though.