We know that Nolan is going to incorporate the concept of time.
We have "Time has come for a new protagonist, Time has come for a new mission, Time runs out."
I believe somebody briefly touched on this but I would like to put emphasis on the word "time" in a literal sense. I believe that Time is actually going to be something tangible in the Tenet universe, hence Time has come and is literally coming after a new protagonist, time has come and is literally coming after a new mission, hinting that time may be the potential antagonist, similar to how Projections in Inception affected certain ops within dreams...
How will this be portrayed? I don't know.
My second theory focuses on the Sator/Rotas square.
There are 5 components that complete this square.
First, we have SATOR - nominative or vocative noun) (from serere=to sow) sower, planter, founder, progenitor (usually divine); originator; literally “seeder”
Next, we have AREPO - unknown, likely a proper name, either invented or, perhaps, of Egyptian origin, e.g. coded form of the name Harpocrates or Hor-Hap (Serapis).
Then we have TENET - (verb) (from tenere=to hold) he/she/it holds, keeps, comprehends, possesses, masters, preserves, sustains.
Followed by OPERA - (nominative, ablative or accusative noun) work, care, aid, labour, service, effort/trouble; (from opus): (nominative, accusative or vocative noun) works, deeds; (ablative) with effort.
And finally we have ROTAS - rotās, accusative plural of rota) wheels; (verb) you (singular) turn or cause to rotate.
Thought 1 - Nolan will incorporate these concepts into characters and potentially their names will start with the first letter of each of these concepts - each of them will represent one of these components.
The reason I believe this is because in Inception, the characters first letters of their names spell out DREAMS PAY.
Thought 2 - There may be a significance/symbolism in the word OPERA. We know that one of the confirmed shooting locations is the Oslo Opera House in Norway, so there may be some significance here, but the question is what will it be?
In terms of characters - I can see there being a character that embodies the definition of Sator (potentially JDW who was rumored to be the one who is able to jump from the past to the present and the future). He could be the originator, the planter, of whatever the conflict/plot is.
We have TENET, which will be a character who is responsible for sustaining, preserving something (probably preserving and sustaining Time? bc Time runs out, right?)
And then we have Rotas - the one who can manipulate (or rotate/bend) time. Also potentially the antagonist.
Character names could possibly start with the first letters of these words.
Another thing to note - the gas masks we see will definitely be an integral prop used by numerous characters throughout the film.
With all this being said, what if Tenet isn't a sequel, but a side-story that's in a mirror universe (building off of mirror universe theory from another post in this thread) of Inception or interstellar?
Just some absolutely crazy theories and thoughts but would love to here what y'all think.