So I have a Spring iPhone 4S now (which has both CDMA and GSM radios.) Does this mean the phone can work on GSM carriers in the US provided the phone is unlocked first?) I ask because there is always that chance that an unlock could pop up at some point in the future and I wanted to know if that happened, could I use it on T-Mobile?

Also, if T-Mobile became an offical carrier for the iPhone (hey you never know) would Apple update iOS so that any current CDMA/GSM phone (iPhone 4S) would be able to run on T-Mobile's network without a hack unlock?