iOS 5 will not be available for iPhone 3GS

The iPhone 3GS has been released two years ago, so would it be able to work with the upcoming iOS from Apple?
Mobile phone blogger Eldar Murtazin stated on a tweet that that Apple won't update iPhone 3GS for the new iOS instead Apple will update iPhone 4 for it. The true question is, what would you do with your iPhone 3GS after iOS 5 comes to the market?. If you are addicted to Apple products like me, you probably won't stand not buying the newest version of iPhone.
I agree with Murtazin, i think iOS 5 won't be available for other versions than iPhone 4.  It is likely that iOS 5 will include many advanced features that require heavy lifting from the graphics department, and the iPhone 3GS simply won't cut it. Rather than going through a performance-based customer service debacle like Apple did when it released iOS 3 for the original iPhone or iOS 4 for the iPhone 3G, I think Apple will just leave the 3GS off the list of compatible iPhones for iOS 5.