I work at a shop, we don't carry Specialized/Trek, we used to do Trek. We don't for the simple reason that anything in the aluminum frame and down, Giant makes Trek and Specialized. They have always done that and unless the tide of economics changes, it will continue to do that. The carbon stuff, as far as I know, are made on this side of the pond, this has been the information that I have found in recent years, I don't know if this still holds true.
Though we are talking about two different things here, if we are arguing about quality and all that sort of stuff, then if all the bikes being built are in Asia, then that's where all the quality control people will be. I like to say to customers that if the barbecue fire is on the other side of the island, people with hot dogs and hamburger are likely going to be there too.
If we are talking about the "brain drain", yeah then that's happening. It's not just in bikes, it's in every single industry that corporations are able to make for cheaper with overseas labour.