It has to be done before the factory batteries expire and have to be replaced. The amount of toxic waste and cost of disposal will double the sticker-price shock (that came even with govt. subsidies). Try selling a $40k+ car used when it will cost several grand to replace battery. Last year the list price of a Volt EV HV battery pack wass $15,734.29. Plus installation. And now there seems to be no limit to fossil fuels due to fracking improvements in the past decade. Texas actually exported, rather than imported, more oil for the first time in history this month.
It you weren't so dumb you would know that the Volt is a PHEV
Leaf, which is an EV, recently announced rebuilt batteries for their older models at $2850.00 installed plus trade in of old battery