It's not possible to produce the amount of meat needed to feed our massive population while treating animals humanely.
There are really two options to deal with this:
Most humans in the world become vegan -- sounds great but it's not gonna happen
Reduce our population to sustainable numbers (by eliminating the driver of the population explosion, i.e. fossil energy) -- maybe also not gonna happen
Edit: What (do I think) will happen? We'll continue as we are now as hundreds of billions of animals are tortured until our civilization collapses. This will happen because we were all brought up under a state and told that defending ourselves, our communities, our animals, is wrong and illegal.