I'm not a vegan or a vegetarian or whatever, hell, I'm practically a carnivore. But these questions don't seem that hard or hugely important to the idea to me. You just need to make the realization that just because somethings the good thing to do or the right thing to do doesn't mean that absolutely every aspect about it will be an upside.
What to do with the animals: Stop breeding them/euthanize them. If everyone suddenly turned vegetarian for some reason I guess you can burn the bodies. Some will be kept in zoos of course. In some cases they might be releasable, but probably in most like you say they wouldn't be.
As for all the places and people involved in the animal product industry, it'd sure suck for those places and people but economic shifts happen all the time. Eventually the areas would be repurposed or abandoned and the people would find other employment.
As much as it's nice to imagine some better world where the animals are re-homed as pets (or well-treated work animals, or non-artificially-inseminated dairy cows), how many people would really have the energy or inclination to care for some fucked-up, traumatised unhealthy critter that's spent its whole life in a factory farm?
Short of some really far-fetched pipe dream scenario where humanity collectively realises its crimes against other species and expends the resources necessary to terraform some nearby planet as a home for its freed animal-slaves by way of atoning for its sins, putting them out of their misery is really the best/only realistic option I can see. 'Course, we're a long way off from having to make such decisions yet, anyway.
There's still a lot of work to be done - the meat industry sure as hell doesn't seem to be losing any steam, even in the year 2017. Kinda horrifying how commonplace it still is to see huge signs in shops depicting cuts of meat, or to have the front page on whatever catalogues one is sent covered in advertisements for and graphic illustrations of discounted dead stuff.
A friend recently told me how the global percentage of vegetarians was some tiny number, and expressed his disbelief at that statistic - but it seemed believable to me. Look at how ingrained the act of eating meat still is in our culture, even as more and more people realise the wrongness of it. Here in Australia, "throwing snags on the barbie" still usually refers to sausages consisting of actual meat, and steak is worshipped like some sort of minor deity or the equivalent of a patron saint.
It seems like a large percentage of the growing number of vegans/vegetarians who
would feel strongly enough about the meat-eating issue to try and combat it are foolishly caught up campaigning about other, less important political issues like human migration and racial politics and whatever other so-called "problems" the hivemind tells them it is fashionable to care about. Humans are humans are humans, whatever their colour or creed. They all contain the potential for limitless evil and, until they prove themselves to be "good" or at least the more-attainable "decent" they are deserving of everything that's coming to them.
[/rant]
...Hoo,
sorry. I seem to have gotten somewhat worked up there.
It is a subject I think about a lot and which aggravates me greatly - it seems that most of my fellow herbivorous humans are "left-wing" in other aspects of politics as well, and are too caught up in the whole, silly social justice craze to remember to do anything to help animals
other than humans. Not going to redact what I wrote, because it is what I believe, but at the same time I am not intending it as a verbal/textual attack on anyone here. I just get touchy whenever anyone discusses 'veganism/vegeterianism/animal rights' or related topics in disparaging terms and feel honour-bound to defend them.
Fakeedit: to introduce some levity into this post I shall weigh in on the current discussion: ham is bland (unless it's that "honey ham" stuff), bacon is extremely overrated (unless you fry it 'til it's crispy, then it's only severely overrated) and spam is freakin'
horrifying. This much I remember from my omnivorous childhood.