There isn't anything you can't do but then again we don't really need fifty "Jean Greys" running around just be creative because even if everyone does make themselves uber powerful the villains themselves will have to be uber powerful so it will balance out.
Void

"On a day like today
I looked at you and I
Saw something in the way
You stared into the sky


But I saw you were sick
And tired of my wrong turns
If you only knew the way I feel
I'd really love to tell you"

Keane