Today's environment is an abnormality in history (e.g. individuals wanting to be herbivores) created by the excess of food and technological advances we have. Maybe this is the way to go, maybe it isn't, maybe either options are irrelevant anyway.
You only need desensitization once you are massacring animals on an industrial scale.
Are people likely to be desensitized by not being part of the process of getting the animal to the table? Possibly, but that is an ad-don to the points I made.
How this is not true of our artificial cities, dwellings, and infrastructure? And what do you mean by "abnormality"? Do you foresee human manipulation of our environment receding toward some less-manipulated baseline? It seems to me that people claiming voluntary herbivorism is "unnatural" (not your word per se) should take a look at everything else around them and realize that human life today is pervasively and inextricably intertwined with the "unnatural", which doesn't seem to cause people to raise any red flags about it.
I don't think it's an "abnormality" so much as a development, just as human civilizations continue to develop.
In all seriousness though I think humans have always thought of themselves as a higher form of life because we assume we’re sentient. And only sentient beings can experience physical or emotional pain, right? Even before the idea of sentience, we threw around words like “reasoning”. At some point humans must have rationalized away the notion that animals experience suffering because to this day we still enjoy our hamburgers and continue to leave out pets out in the cold.