Nobody really knows how many years (decades) we will have to wait until the next part of the series will actually appear, but at least there is now an indication that development has already progressed further than one might have thought.
Because for the 30th birthday Elder Scrollsseries, the above message was tweeted, which is particularly interesting towards the end: It says that work on Part 6 continues and that there are already “early builds” that are being played (presumably by the team and bug hunters).
And also!