Hopefully the Namor movie won't bomb.
Though I have to say, Namor movie has a lot better chances of surviving then Aquaman movie...sadly, the Super Best Friends have still left their devlish mark on Aquaman. Namor isn't as known as Aquaman, so public wouldn't have as negative feeling on him...especially as he is portrayed so badass these days (well, he always has, it's just that the speedo lowered his badass-factor by 70%).
As for DC movies I think would be great...
Flash (Barry or Wally, As the Rogues Gallery or Zoom as villain)
Green Lantern (Hal, as Sinestro as the last villain)
I always pictured that a Flash movie didn't even need to be done with the Flash outfit (cause frankly, I'm not sure any one can pull that look off in real life). The Flash could be a teenager much like the one who appeared in Smallville with just red clothing.
And I think Zoom would make an awesome villain.