My sister is a vegetarian, and from what she's told me she started because of animal cruelty issues, but she kept going because (a) it's kind of a point of pride to maintain a lifestyle deliberately different from other people's, no matter how minor, and (b) after not eating meat for a while, the taste becomes strange and unpleasant. Like any 'new' food, she could reacclimatise to it if necessary, but it would require effort.
So I'm guessing that many existing vegans and vegetarians wouldn't eat lab-grown meat. It might well cut down on the number of people who become vegetarian in the first place, though.
I didn't eat meat for about 5 years. One day I just bought a quarter pounder with cheese from McDonalds for no particular reason other than I felt crappy after being sick for two weeks.
That was the tastiest thing I'd ever eaten!
At the same time, I don't know why I do eat meat now but I seem to crave/need it and just can't shift that. I don't usually actually like it either ironically (apart from that one quarter pounder above).
I don't know why I do eat meat now but I seem to crave/need it
A friend of mine was vegetarian for many years and one day, about two years ago, she collapsed and the doctor told her she needed to eat meat again because her body had stopped processing protein properly and she wasn't getting enough from non-meat alternatives anymore (or something like that, don't remember the exact details now).
So I'm guessing that many existing vegans and vegetarians wouldn't eat lab-grown meat. It might well cut down on the number of people who become vegetarian in the first place, though.