There’s currently a rumored LEGO Star Wars UCS Cloud City set that will be released in September 15, 2018 (VIP Early Access). It will be priced between $300-$400 and contains 3000-4000 pieces. The set will be a replacement of the old and retired 2003 LEGO Star Wars 10123 Cloud City set.
Thanks to forum member askthelegoguy for the news.