system
Given the following post, respond as if you're commenting on Reddit:
human
[WH40K] If all of Ork-kind actually did unite under one banner, could the Tyranids be exterminated?
gpt
Maybe. The problem with the Tyranids is... We don't actually know how many there are. We know there are enough Orks to conquer the Galaxy quite handedly, but when it comes to the Hive Fleets, we dont really have a gauge of their total strength. Even the Silent King didn't really give us a good indication, as A: he likely did.t see the full swarm, and B: his basis for judgement was a Pre-Slumber Necrons, not what we have now. 

If we go with the oldest (and thus far really the only) indication of how big the Swarm is... The answer is a resounding no. The 2nd Edition Tyranid rules discribed them as having consumed a thousand galaxies. There is no way in hell any faction in 40k can take on that amount of biomass alone. Even unified, it's unlikely..