How soon before Marvel announces Namor to counter Aquaman?
This year? Next year?
Should they introduce him as a villain or a hero?
If they go the hero route he should probably get his own film first. If they go the villain route he could pop up in Avengers 6, Black Panther 2, or Marvel's Fantastic Four.
Costume wise do you go with the classic green speedo or a more modern look? If you cast an actor with good abs you gotta go bare chest, but if your just casting someone and not worried about physique I guess he can wear a shirt. Or they could go the Namora route, but that seems unlikely.