If you look further afield, and at the international markets where the iPhone is sold, you find that by 2013, only approx 2% to 5% of the population will be covered by 4G LTE networks, whereas about 90% will be covered by 3G networks.
It makes me wonder if an LTE iPhone is really worth having before June 2013?
Some posters have commented about the backbone networks that support LTE, and yes, they will certainly need serious upgrading. The data to be send to handsets will need higher data rates, but will take significantly less time to download say a webpage, so carriers will decide to raise the contention ratio, at least in the short term.
This means that at times, a user might experience amazingly fast downloads, whilst peak times will be no better than now, or could be worse as Smartphones and use of them increases.
In terms of battery life, I do remember my first 3G phone, a piece of ****** made by LG, and even though it didn't have much processing power to download webpages fast, whilst on 3G networks you could actually watch the battery gauge drain away. Downloaded a podcast one day whilst waiting for a train and went from 90% to 25% in 10 mins!!
The same may be true for some early 4G phones, but battery technology has moved on leaps and bounds since 2003, so it won't be as severe. Coupled with the fact that silicon manufacturers now understand how to build in power management into each component, then it should be ok.
Personnally, I find that the majority of time when I need fast downloads, that I'm in a wifi zone (at home, work or out and about) and have only only downloaded 2gigs of data via cellular in the past 10 months. So will 4G change my life?? Maybe, if there is a 'killer app' out there that would need it!
Will I still upgrade to the iPhone 5 if it isn't 4G? Simple answer, yes. i.e. it's not a deal maker and nor a deal breaker.
Phil