I agree that you will not see the solid rear axel on the camaro at all. The costs associated with designing another camaro with a solid rear axle would probably too high to justify the low demand for this option. They would essentially have to completely re-engineer the rear for this. Not to mention the platform that the Camaro will be built around may or may not even allow for a solid axle.
Who knows, maybe the new platform will work well with the IRS and will not have the same problems that were prevelant in the GTO