The fact is NOBODY makes a true 4G phone and no cellular provider in the US has a 4G network either - the ITU made this clear. Nobody will be close to 4G for at least a few years.I'm sure there are various ways to get more life, but the fact is that the current crop of 4g phones are juice hungry, and I don't see Apple jumping on that 4g bandwagon until the technology has matured.
http://news.cnet.com/8301-30686_3-20022011-266.html