This whole thread is a thought experiment. I made a single simplifying assumption, for the sake of clarifying the particular qualities of that thought experiment: that voters would understand the policies of the second and third parties to be identical. In that case, IRV isn't "unlikely to break 2 party dominance", as you claimed above. So, that claim isn't universally true. It might be true in some circumstances, but we don't know what those might be. You'll need to explain more carefully why we should reject RCV in favor of some more perfect alternative.