Godlike in power
This is like your idea. Many of the same considerations need to be made.
Are you sure that your players will choose to be Heroes and not villains?
What percentage of the population is going to get powers?
Will the powers come from a single source?
What NPC superbeings will appear? and who? (What if President Bush got powers? or even the town's mayor?)
world that is unaware of super-powered people.
How will the long time (secret) supers react?
Will the secret history of the world cause major shifts. "Everything you know is WRONG
IF they hide their powers, or even refuse to use them, you'll need to have a contingency plan to force them into action. I've been in game where this has happened.
Suggest "Mentor": Have an old super
who has made it his bussness to track down and train newbies. He mentors them but does not push them to use their powers in heroic or villainous ways. - This is not needed with all of the PCs, just the ones who are hiding from their powers.
A man without religion is like a fish without a bicycle.