They already did it.
Android has numerous applications. Angry Birds, Doodle Jump, Pandora, ETC.
The reason why the App Store is looked at as a revolutioninal market, is because the User Experience just feels so smooth when playing games on your iDevice. The A4/A5 chip. GameCenter. ETC.
I don't think Anroid will ever be superior gaming wise, as the iPod Touch is already the best Mobile Gaming Platform, but it's definitley already winning over some consumers.
iOS will live on forever!