Well, since we currently have no other manned military access to orbit, I dont think we can afford to view China's ambitions to get into space as entirely commercial.
I recall a statement some time back of an Air Force General, whose name I cant recall, to the effect that, "We must not only be prepared to fight in space. We must also be prepared to fight our way into space."
There's a certian ominousness in that, which informs the opposite of your view, to me, as much as I respect it, however.
You raise a good point. No one can predict the future and there's always the possibility that manned missions may be necessary to secure our military hardware in Europe.
I do think it will be at least 10 years before China can do anything realistically threatening in space, unless you're talking about "killer satellites" which don't have anything to do with manned missions and can best be defended against with technology, not people.
In the meantime, we can keep our edge with fewer flights and fewer people on each flight while going full speed ahead with putting the most sophisticated technology in orbit that we can develop (which I'm sure we are doing).