Definitely no Arya sequel:
https://www.comicbookmovie.com/tv/h...liams-comments-on-aryas-fate-spoilers-a168497
https://www.comicbookmovie.com/tv/h...liams-comments-on-aryas-fate-spoilers-a168497
With D&D being busy with Star Wars there is a chance that they get good writers instead.
It wouldn't surprise me if internally those two will be blacklisted by HBO.
I'm pretty sure you are incorrect. HBO is unlikely to share our sentiments about those two. Game of Thrones was HBO's pride and joy for years. It was pretty much the only reason to have an HBO subscription. D&D's writing may have gone downhill as they surpassed the books, but their efforts to adapt the books into a succesful tv show will not be ignored by HBO. All D&D have to do is tell HBO they want to make a new show, and HBO's response would be "How many piles of cash do you need?"
I am not so sure about that.
HBO wanted D&D to make more episodes and even more seasons (it is their cash cow after all), only to be told by them they don't need/want it. And then they delivered something that disappointed fans, damaging the brand, and is especially criticized for being too rushed and that there should have been more episode.
I don't think that HBO is all that happy about how D&D handled the last season.