The Georgia tax credit was seen as a "free car"--which with leasing it was virtually free. Then all of those leases came up, they turned the car in and the resale plummeted. For example, that "free car" was $32k, the residual was $17K. Used leafs are anywhere from $6k-9.5K 2 years old. I bought my '15 for $9,300 with 4800 miles. From some discussions with the Dealer, who had lines of lease turn-ins, most did not buy another EV. Some bough PI Hybrids from other manufacturers but most went back to oil burners.
To equate the sales in Georgia to be true EV converts would be misguided. There is no demand for the cars and only sell with low lease rates. The $7500 is important, but a bad taxpayer investment in what is now a mature technology that is not being accepted by the market.
California's mandates will require OEM's to lose money on each car sold to comply. That cost will have to be passed to oil burners to recover the costs.
The $7500 is insulating OEM's from facing up to the reality they have to make EV's with range, charging times and cost close to the oil burning counterparts and any Fed credit should be moved to technology that needs investment, such as fuel cell cars