See, I'm not an Apple fan by any stretch of the imagination, but I was afraid of this problem. Too many "similar" phones/devices running the same platform, delaying the upgrade process.
Why can't smartphone OS upgrades be similar to Windows upgrades? From Windows Vista to Windows 7, there's simply 1 upgrade disk for each version of Windows you wish to upgrade to, times 2 for 32-bit and x64 systems. There isn't one set up upgrade disks per vender, per computer which has different hardware. Surely, you end up with bloatware on your computer, but that can be controlled.