It is kind of amazing that no studio has made a true, open-world, first person fantasy RPG to fill the Skyrim void. It feels like a $1,000 bill just waiting to be picked up up off the ground.
In May 2011, CDPR released The Witcher II, modeled on Bioware's games rather than attempting to elaborate on the first Witcher game's formula, and achieved substantially greater sales relative to that first game, only to find themselves eclipsed in November by the juggernaut of The Elder Scrolls V: Skyrim. Aware that Bethesda would subsequently work on another Fallout game before returning to The Elder Scrolls, CDPR spent the next four years on an Open World Witcher sequel, modeled to a considerable extent on the previous three Elder Scrolls games, and released it in May 2015 to achieve another considerable boost in sales, if not quite comparable to Skyrim's long-term commercial success. Bethesda released Fallout 4 in November 2015 and was disappointed that it did not replicate Skyrim's immense sales (though it sold quite well on its own terms).
The problem since then is that CDPR decided to establish another IP, in a science fiction setting (Cyberpunk 2013/2020) acquired while working on The Witcher 3, while undoubtedly expecting that Bethesda would immediately initiate work on the next Elder Scrolls game. If both companies had taken another four years to complete their games, this would have seen Cyberpunk 2077 arrive in May 2019, followed by TES VI: Hammerfell in November 2019. Instead, Bethesda somehow spent 8 years creating an Open World space RPG, that isn't Open World, fails to make use of space other than spaceship combat, and isn't much of an RPG. Meanwhile, CDPR took a year-and-a-half longer than expected to release Cyberpunk 2077, and only managed even that by releasing it in a buggy state lacking many intended features and probably much other content.
If Bethesda is able to complete TES VI in just four years (which it won't accomplish), 16 years will have passed between entries in the series. CDPR does seem to have followed the obvious path of returning to the Witcher IP for its next game, but they apparently need more than four years to complete it, so it won't be releasing in 2024, and, considering no details have been confirmed yet, development might take much longer than four years.
A disaster for both companies.