As far as the Alpacas, I'm under the belief they'll go with the 'path of least resistance' when they leave the Tranch. i.e. They are going to open whatever gate (as they abandon property) so they can become wild Alpacas. I also assume they'll immediately die from the list of obvious reasons.
Penny and Co like to larp as ranchers, but there's no reason to believe any of them would kill the flock, directly, if it meant less hardship for the animals. And with the sheer number of animals, I don't foresee relocation as a possibility. (Maybe if they put in effort and was able to move them piecemeal, but that's effort they don't have)
So they'll open the gates, leave, and feel bad for a minute. But after a few days, the tranchers will have already moved on emotionally since they can lie to themselves and think the animals are fine in the wilderness.