As others have said, it's only been recently that we've been divorced from the actual process of slaughter and meat preparation. It does drive me nuts that people are happy to eat meat but wouldn't think of harming an animal. Most of the people I know who are squeamish about this are girls.
Tell that to the rednecks.
I suspect this is more likely to happen "post -apocalypse" ie after some event that means (in Britain at least), we're running around looting, killing etc. Take the infrastructure down and people can't survive.
I went vegetarian for a good few years because of a girl. Consequently, I just stopped eating meat including fish. Even now, I can go weeks without eating meat if I don't feel like it. However, I have developed respect for animals/meat and appreciate where food comes from. In the end it comes down to instinct for survival. It wouldn't surprise me if even the hardest vegetarian turned to cannibalism to survive.