I highly doubt that common domesticated animals would be destined for extinction. It is very likely that they would struggle to survive 'in the wild', but the fact is that 'the wild' is no longer quite as wild as it used to be. I really doubt there would be many predators for previously domesticated cows to worry about in most parts of the world, for example. Same would go for chickens - the amount of flightless birds that manage to survive against what you would think is common logic lead me to believe that chickens would manage just fine as well. Definitely not on the scale that they are living on in the world right now, naturally, but nowhere near extinction. HOWEVER, if they WERE to near extinction, the fact that they are so easily domesticatable and we have such a knowledge of how to raise them already learned, we as humans would have absolutely no difficulty in domesticating them and ensuring their survival as a species within our control, rather than in the wild.

Further, your statement "The only way we end their circle of suffering is by getting them all killed" is misleading - we would not be getting them all killed, we would simply not be breeding them to excessive amounts anymore. We would no longer be aiding in their uneccesarry birth, and thus population boom, is a more accurate statement. Now, if you mean that we would simply be releasing all of the CURRENT animals into the wild in one fell swoop, then yes - many would be killed, but almost definitely most by simply depleting the natural resources needed for survival, thus starving themselves out. Also, that is a huge, and frankly, silly leap in this hypothetical situation. If by some mandate we suddenly all stopped eating meat today, we would not simply release all domesticated animals to fend for themselves and hope for the best.