Yes Anyone Can Install iOS 9 Right Now, But You Should Wait
Update: iOS 9 has been released, you can download it here or install from the Settings app. This applies to all users, no need to wait anymore!
Now that iOS 9 has reached the GM build, it can technically be installed on any compatible iPhone, iPad, or iPod touch right now, assuming you have the proper iOS 9 IPSW file. Because it’s the final version of iOS 9, installation no longer requires a Public Beta profile or Developer UDID registration, but even so, you shouldn’t update right now.