We're so far from that being even close to a problem that I feel it's a bit disingenuous to see it repeated so often when vegetarianism comes up. There's a whole lot of meat we can cut out of our diets without any of that becoming a problem.

(And of course, if the soy that is currently fed to cattle is fed to humans directly, we can feed quite a few more humans from that than that cattle currently can, without needing to use more resources. That's not to say it does not come with its own problems, but they're unlikely to be as severe as the ones we get with meat anytime soon.)