Well, I mean it is possible to downgrade your software, all you have to do is find the iOS version you're looking for online, and when the iPod is connected, (if you're running Windows like myself), shift click (Shift+Click) the 'update' button on the iPods main menu, and instead of just updating to the newest iOS, it will ask you to locate the (iOS) file that you want the iPod to run on, in Windows Explorer.
This allows you to find older iOS versions just in case something to the newest version (such as iOS 6) isn't to one's personal preference.
I was just wondering, because I know many people with iPhone 4S's and many of them seem to not like iOS 6, and I'm not too keen on it myself. Since I will soon be getting an iPod Touch 5g (which naturally comes with iOS 6 preinstalled), I was just wondering if the hardware on this newest iPod would be able to support the software for iOS 5? Y'know, just in case.