As soon as that happens they will start dropping the price of "smart" cars to undercut the market. That's how monopolies work. One major reason they can do that is that a dumb car model sees the manufacturer and dealer paid exactly once. The smart car model sells your data and requires maintenance to a point where some cars just won't start if it isn't done. This renders continuing income to both the manufacturer and the dealer.

For proof of concept, look at the smart tv market. Dumb tvs largely aren't around because the price of the hardware is subsidized by the money they make collecting your data, so a dumb tv of the same specs is always prohibitively expensive compared to a smart tv.

That can, will, and in some ways is already happening to the car market.