They're probably going to finish up with around 9 anyway - the build-time of the Fords is getting towards 8-10 years and the cost of refurbing a Nimitz to keep it service for another 10+ years is likely to be stupendous
IIRC the original out of service date for the CVN-68 Nimitz was 2025 which reduced numbers planned in service to 10 anyway until about 2030.