Well, I agree that 1080P is better than 720P. But I would also say that HSPA+ is a "generation" ahead of CDMA.
Under the old definition, only WiMax2 and LTE-Advanced were qualified to be called 4G networks. If that were still true, no carrier in the world would be 4G.
So, will Apple market 2 different iPhones?
3G-CDMA: Sprint, Verizon, 3 mbs
4G-HSPA+: AT&T, 21 mbs
Hard to justify a switch to Sprint even if they offer unlimited....slower and no data/voice multitasking.