Skyblivion has a confirmed release for 2025, and the devs that Ive spoken too seem quite sure theyll meet their goal and release sometime around december this year. Theyre doing everything from scratch, so all locations including cities and dungeons are gonna be much larger and look completely unique, imo the art direction looks better than the remaster too. Its mostly done by now, I believe a few more dungeons need to be implemented, voice acting has to be added and some polishing is needed but its even playable at its current state.
Skywind on the other hand is much further behind, tho id assume that once Skyblivion is done with the DLCs some modders may join Skywind to help out.
Youre correct to assume that about BS, like I said earlier, most of the Beyond Skyrim teams are horribly mismanaged (Elsweyrs pre release is only like 15% done after 13 years) and most projects keep redoing existing work. One thing to consider is that theyre basically separate teams which share lore, the heightmap, scripts for travelling between provinces and the BSassets file. Also most projects have an overwhelming amount of writers and artists as opposed to the people actually developing the mod. Its safe to assume that within a few more years we will get another pre release, Roscrea and Cyrodill but thats it as they are the only functional teams.
Its funny you mention Elsweyr as after like 13 years theyre only approximately 15% done with their pre release and its mostly just writing/music that thats been worked on. It may as well be dead but they dont wanna admit it.