I've spent a lot of time in the US (visited 30 states so far and have another few planned for the next few months), a lot of friends over there too.
One of the reasons I love travelling there so much is because the US feels amazingly foreign to me in terms of attitudes etc, but because we share a common language and they are quite chatty, generally, it's interesting to explore the differences.
The US (barring the exceptionalism of the coasts) is a lot more conservative and religious than the UK, and is only likely to become more so with immigration from Latin America, Asia and Africa. It's a fascinating place and somewhere I love dearly - wouldn't keep on going back if I didn't - but think that culturally we are two thirds of the way to being European in terms of social attitudes etc and only one third towards the US, therefore the cultural difference would be too great to integrate properly.
However, the US is by no means homogenous - Louisiana, California, Alaska, New York and Dakota are more different from each other than are the UK, Poland, Slovakia and Italy, for example. It'll never happen for reasons of pure geography, and increasingly, race and tribalism - but I hope we don't lose our historical links, as I think there's a lot we can learn from each other (including things we could do better than the other cf gun crime; social equality etc etc).