But who could you possibly cast nowadays? Don't fucking say Ryan Reynolds.
It could be just about anyone who can handle the delivery when in the Mask persona. Jim Carrey's approach to that character isn't necessarily the most appropriate one.
Also, there are several lead roles in the comics, not just one, and pretty much all of them wear the Mask at some point. Stanley Ipkiss is far from the lead in the comics and is equally far from being a good guy.
I guess rated-R, just for the sake of having a different take than the original.
The funny thing is, having read the original comics not too long ago (those Dark Horse omnibuses are great), the movie was actually quite faithful to them. They just substituted the violence with Tex Avery antics. But other than that, it's pretty much the exact same story beats and characters.