They will sell every one they can make. The folks that can afford $100k don't care about fuel mileage and those folks are not impacted by the economy either. ZR1Corvettes go for $130k and don't do any better on gas mileage There is a waiting list to buy them.
Unlike the Viper, a 2013 Vette has an MSRP of less than $50k, depending on the model. The Viper needs a bit more variety and a handful of wealthy enthusiasts cannot generate enough sales to justify the expense of keeping the brand going for very long at the expense of taking R&D money away from other products in the company.