Just do Neon Genesis Evanglion already!
G. Del Toro directing a more adult/mature and have philosophical themes for a mecha (giant robot) & monsters movie would certainly have the giant appeals. Not only that Evanglion is a big and pretty known series for mature audiences throughout the world. I am also pretty sure G. Del Toro himself is a fan and would love to make the movie.
The only problem that prominently showed up is seems to be the Hollywood and US market. It's kindda weird when this movie was a bomb in the US, while many people love it. It's certainly a superior movie in the same genre. meanwhile it was a pure success for Non-USA/worldwide.