@TNT261 point taken, and some i already knew of(and completely agree).
but here's the thing.
when you say 'The best thing we could do for them is let them live on their and fend for themselves.', it's not really the best thing.
if they live on their own in the city, said dog/cat will become strays, which won't be good for the public hygiene and ecosystem. (some birds has already went extinct because of stray cats hunting them)
throw them into the wild, and they'll probably get killed by the wildlife, regardless of the age when you throw them (pup or adult).
the fact is, it's too late to abolish the concept of a pet. best thing we can do in my opinion is :
-abolish the kennel club.(the organization who won't abolish the 'purebred' even tho they know full well it's bad for dogs/cats. they said it's for the animals, but we know it's for the moolah)
-start to cross-breed the 'purebred' to make a healthier next generation of cats and dogs.
-neuter/spay your pet.
-start adopting and make pet shop to only deal with pet accesories/supplies and not the pet itself.
-make laws to deal with irresponsible pet owners.
-make the process of having a pet harder, as in checking 1st if said owner candidate have enough living space/income to support having a pet.
if we live in utopia and everyone does this, theoretically in 10-20 years, there'll be no more strays(or very litte there of), and people who don't deserve a pet won't have them anymore.