It's wrong. While the Exynos chip inside the GSII LTE HD is 1.5ghz, I'm fairly certain that it's not the 4212. The 4212 is 32nm, while the one inside the GS2 LTE HD is 45nm. It's very likely just an overclocked 4210.
However, there is one reason why I suspect that the 4212 COULD (likely won't, but COULD) land in the Nexus Prime. Going down to 32nm is nice for battery savings and for the rumored GPU performance, but it's still at heart the same chip as what's in an existing phone. I don't see this being the key chip for the GS3 next year. Tegra 3 (quad-core) will be out by then, with OMAP and Snapdragon having their quad-core designs our or nearly out. I would suspect that the 4212 is for refreshes only, but the quad-core version will hit the GS3.
The next Nexus would be a great way to debut this die-shrunk SOC, if possible, but then I also thought that the Nexus S would be a great device to debut dual-core, but that ended up being ye olde Hummingbord.