Who says who we could be fighting in 10,15 or 20 years time. In 1980 who thought we would be fighting Argentina 1982, Iraq in 1991 or in Afghanistan in 2001?
If history teaches us anything it is that no one can or should try to predict the future.
Who knows, we could end up fighting France in 2008 or Japan in 2012 or the USA in 2021.
None of that is likely, but it is better to be prepared by retaining the capability than to fall into the idea that we would get help from the USA. After all the good old US-of-A really stood by us in 1956 didn't they and I am sure that could never happen again right?