The US cell market is different than Europe, outside metro areas it is very spread out hence it needs more towers (and takes longer time to upgrade). I highly doubt Verizon or AT&T having any serious coverage before Spring.
What I think Apple is likely to do is release iPhone 5 as 3G, go back to the June cycle and release an LTE iPhone 6 in June 2012, which would be only a few months after LTE becomes 'the' standard.
What I think Apple is likely to do is release iPhone 5 as 3G, go back to the June cycle and release an LTE iPhone 6 in June 2012, which would be only a few months after LTE becomes 'the' standard.