For legacy cars the likely answer is that people buy the $250 dongle. For new cars this will cost a few hundred bucks in parts and labor (or let's say 1-1.5% of the sales price) and it will be required surgery on your brand-new car.
Who is going to pay for this? If it's Tesla, then the smart move is to put CCS into cars right now (and as a side benefit, standardize their US and European models [edit: nevermind this bit, not the same standards].) If it's the customer, then it's an annoying non-trivial cost you'll have to bear. Yuck.
