iphone help

Hey guys, I pre-ordered an iPhone 4S yesterday. The contract is 2 years long and an iPhone comes out every year. What if I want to upgrade to the iPhone 5 which is a year from now, will I have to pay that $500 (whatever it is) price point or is there a way to pay the $199 and transfer the current contract to the new iPhone. If not, what will you iPhone users do then? Also, I paid $199 for the 4S and its the 16GB Black Model with a $15 month contract (200MB) and the AT&T Nation FamilyTalk 700 calling plan. The one time fee was $18.
mod edit: Removed link

tbh there /should/ be a way since the iphone 5 will be out soon (depending on where you are) but i'm betting you're gonna have to pay the full amount
always a catch for these sorts of things and the buyer is not usually on the convenient side ;_;