Paul Rudd would be great in the role. I can think of other people I think would also do a great job, but Gordon-Levitt is not among them, so, if the previous news was true, then I'll be really happy if this news is true. Gordon-Levitt would make a great Dream of the Endless in Sandman though, so as long as WB doesn't screw up yet again, he has his own bright future with comics properties.
I wonder which Ant Man Rudd would play? I guess at this point, listening to other news on the project, Hank Pym is unfortunately unlikely. I could see him as any of the three, but probably mostly as Scott Lang.