So applying that same logic, billion here we come?
Though yes, the Dunkirk post was made on June 1, 2016 after filming began and we already knew the subject matter, while we know basically nothing concrete about the 2020 film other than the three lead actors.
Edit: So June 2, 2019 is the cutoff date for your "wow, you really nailed it!!" predictions, people!
This is being released on the same day as the Bob's Burgers movie. How much money do we predict that will make opening weekend? Trying to gauge the competition.
I'm a little more worried about Disney's Jungle Cruise, which comes out the following weekend. Nolan's film will be fine obviously, and it will probably make more money than Dunkirk overall, but that also benefited from not being up against a Disney film starring Dwayne Johnson.
Out of Nolan's recent blockbusters, Interstellar seems to have had the stiffest competition upon release with Big Hero 6 on the same weekend and Hunger Games: Mockingjay Part 1 out two weeks later.
I think counter-programming will help Nolan's film in this case. I don't think the same people *legitimately* interested in Nolan's film will be choosing Jungle Cruise or Bob's Burgers instead, and vice versa. Really, you're looking at two weekends for a wide spectrum of movie goers, and everyone wins.
Honestly though, I'm pretty sure a Nolan Time Travel Summer Blockbuster is going to be feared by everything being released for a *month*. This isn't necessarily a niche thing like Dunkirk; this is fun, mainstream popcorn. It's going to be huge.
I find it unlikely that Tenet exceeds Inception's take, and if it does, it will be by the hands of inflation. Inception was almost a cultural phenomenon, you still hear its influence today from "[insert anything]-ception" to the style of trailer music it helped pioneer.
Inception also benefitted from having Leonardo DiCaprio as its lead, the man who starred in Titanic and certainly has an extremely large mass appeal. John Washington and Robert Pattinson don't particularly.
Considering also that theater sales are slowly declining and have more competition now than they did in 2010, Nolan would need to make Tenet an even greater achievement than Inception if he wants to surpass the latter. I don't find that too likely.
I'd guess a haul of 600 to 800 million, on the lower side of that range.
If Nolan wants to break a billion again, he'll probably have to do it through another franchise. He could almost certainly do it with Bond.