That's a grand debate with other forms of societally unacceptable pornography as well, and one I wish people would get over their hang-ups about researching - i.e., does masturbating with a non-living representation of something (image or doll) reinforce, or weaken, the desire to act out those fantasies with something living? The Supreme Court heard a case with elements of this a few years ago as it related to hand-drawn images with sexualized children, though I don't know the details.
To me, I don't think that question has a good answer without research. I personally don't think "possibly could" is a very strong scientific statement, and I'd prefer to see more research on the subject before those kinds of claims get made...I think there are some of them tend toward scaremongering, at present.
As far as the girlfriend replacement goes, who cares?
To me, people are different, and notions that we "should" be with someone are not usually worthwhile. If these guys want to buy the newer, better sex dolls, I have no problems with that at all.
The Piers Anthony "Apprentice Adept" series actually goes further with this, and describes a society where robots can actually be made that are indistinguishable from actual humans in terms of appearance and intelligence. The use of these robots as sex partners is a theme that gets touched on briefly. I think it's good reading if people want to actually think on the subject for a bit. Those who just want a new moral panic might want to skip it.
