I don't think that the technology really does exist yet, at least not at a feasible level. Sure, you can overclock some IPSs, but at that point they're way out of rated spec; it's a bit like expecting AMD and Intel to release their desktop CPUs at 4.5-5Ghz stock, because they can often be overclocked to that level. Plus, a huge number of people wouldn't be able to use them (at least not at full speed), due to limitations in the GPU (for instance, AMD users can only get 85hz out of Catleaps, I've read).
If LG managed to make a feasible 120hz 1440p+ panel, I've no doubt Asus would use it, and I wouldn't be surprised if Dell and Samsung did too, but I don't think they can yet. It doesn't help that the market for these hypothetical panels is actually pretty small, either.
If LG managed to make a feasible 120hz 1440p+ panel, I've no doubt Asus would use it, and I wouldn't be surprised if Dell and Samsung did too, but I don't think they can yet. It doesn't help that the market for these hypothetical panels is actually pretty small, either.