Already saw this movie Logan Lucky and there was a cute hint to this issue:
Never read them and watched the 1st season of the show and never really got into it for whatever reason. At age 75 and supposedly this one and another after? He better move it at this rate he will have to live to 100 to get both out.
Worked for the Wheel of Time eh! 'Time to call up Brandon Sanderson again from the bullpen.
What you suspect actually....makes a lot of sense. I can believe that.He did finish it. The show ruined the ending so he isn't motivated to actually finish that book series and now is focusing on other stuff where people don't know and hate the ending.
Of course, with GRRM long since bowed out Sanderson is the best fantasy writer in the business. People will have their own preferences but he can't be beat on the overwhelming level of quality content.He actually did a fine job.