It's not that convoluted if they just bring Momoa into the DCU because Aquaman 3 as an elseworlds film would literally make no sense (it's part of the DCEU so it can't be "elseworlds"). But yes if it does do poorly then all the "they'll make an Aquaman 3" takes will age like milk.
I have absolutely no idea how this somehow dips below $270M WW with a holiday release. Do you have a breakdown? Is it gonna open to $30M with like 3x legs?
Which "0.00001% chance it's happening" would be more surprising? Aquaman 2 above the first movie worldwide or Aquaman 2 worldwide below Black Adam worldwide?