Regarding a Corvette supercar, I think General Motors would make a mistake by creating two markedly distinct vehicles under the Corvette name.
It would weaken the Corvette name by creating a dichotomy of "haves" versus "have nots" among Corvette owners - those with the low-priced versions against the high-end "real" Corvettes.
In the Corvette's nearly half-century of production, option packages like the ZR1 and ZO6 have offered higher performance without significantly changing the base Corvette design. I also think that approach of upscale optioning makes more financial sense than creating a totally new (and probably low-volume) model.
GM should stick with the current formula that has worked well so far and maintain the Corvette's strong, unified image.