They have already made plans to repair the cars - they will be sent to a special Chevy shop to evaluate how to restore. Quote from their press conference:

Highlights of the press conference include:
- This is very common for this area, what's not common is for a sinkhole to swallow eight Corvettes.
- It is repairable. The building foundation and structure is in good condition.
- They will be securing the sinkhole and surrounding areas to ensure that even if we have sinkholes on the property in the future it will not affect the Museum.
- It will take 2-3 weeks to stabilize and secure the area (red spire, walls of the sinkhole) then the process of vehicle recovery will begin.
- They will be making sure the sinkhole is safe and that no further damage will occur before starting vehicle recovery.
- It will take 4-6 days to retrieve the vehicles
- After that, they will replace earth and the floor system
- They have a good plan and it takes action tomorrow with no problems foreseen
"We are confident that it will be done in time for the Museum's 20th Anniversary Celebration in August. You won't even know that this has happened," said Wendell Strode, Museum Executive Director