If it's a summer 2020 release and the movie gets shot mid 2019, we'd get casting announcements in the first half next year, which would mean an announcement at the end of this year or early next year.
However, in September 2015 the release date for the then unnamed Nolan movie was announced, and we're already past that point.
Let's face it, Nolan is already enjoying retirement right now.
I think all this delay we're experiencing is due to the new status Chris is in. He's already a legend, and has nothing to prove, now he's working for history. He has no cravings, he will be writing and designing everything to perfection. I think it was very clear in Dunkirk, where the whole film was a perfectly chiseled piece. It's very noticeable that when he came to the beach to shoot with all the crew, he had already studied all the shots at an infrequent level. In fact, he was in town before writing, and even made a video with his 16mm camera of the arrival at the beach through the alley. He inspected the location and then wrote.
I don't expect less for his next film, and I'm sure it will be even bigger.
I've been saying this for a bit now. I think he is linning up his next movie to come out the same year as the new Bond movie. Release date for the new Bond movie is early 2020. Nolan I feel will gun for the same year release so he can take over the next Bond run. Bond is just too perfect for him. He has addmitted love for the character.
Listen Nolan can get anything green lit but it's been awhile since his Batman success. I think he realizes the benefits for him getting anything green lit if he helps.the studios with their franchies. It's how Inception and Interstellar got made.
Think he lines something up for 2020 (hoping a western lol). Then he takes over Bond and repeats what he did with Batman. A trilogy with some daring original work in between each movie with the studio on his good side....because let's face it a Nolan Bond would make bank.