The title is a tautology. I can't help but feel that anyone from country X will every be integrated into any other country, as long as they still want to be themselves. Which is what the author never really states. Had he bought into the materialistic lifestyle, asked everyone how much money they made, and insisted his kids cram for elementry school exams, and toed the party line (whatever that may be), then maybe he would've been considered Chinese (I bet he'd say you still wouldn't but he didn't even consider that possibility). But no, he wanted to be a Westerner in China, and by definition, never become Chinese.
I lived in Europe for half of my life before age 30. I was fluent and mistaken for a native of the country where I lived. Yet, I could not help but retain my American perspective; I don't think I could give that up even if I wanted to. So even if I blended into the culture and wanted be a native, I could not feel like one myself. I came "home" to the US and don't feel American anymore either--I think that will be the author's fate in Britain. I have American friends still there, native by any standard, yet still consider themselves American by choice.
So I think it comes down to giving up one's identifying culture. The ironic thing, is that Chinese (and many other foreigners) do it all the time when they immigrate to the West. To me, that is the quandary of immigration: how do they manage to embrace the host culture so much that they no longer identify with their native one. It seems so much easier to do from East (India, China) to West (US, mostly). It seems like it's much easier to go from a culture of community to one of individuality than vice-versa. Why is there a lack of symmetry?