Rather like Flymix, I'm also "dual" (the U.S. doesn't like the idea of dual citizenship mind) & working in the U.S.A in an occupation I enjoy very much. I like the people here & the environment; lifestyle is excellent.
However, given the chance, I would get back to the U.K. in a heartbeat. I fully understand how fortunate I am to have a choice & am lucky to have been accepted by my adopted country i.e. I'm not ungrateful in the least but after some years of being away I really miss too many aspects of life in Britain to say that I could see myself here forever. And yes, I do get back to the U.K. fairly regularly so I'm not pipedreaming about a long gone era.
And for the reasons CanAV8R mentions, it's time to start planning now...