I am confused about this too. It seems like 99% of sites using maps would be doing it client side in which case the cost change wouldn't be a big deal, but maybe I am missing something.
They are talking about client-side APIs, but the limits are not per client IP address. They can look at the referer header to see what site embedded the map.
Google blocks you from seeing referred search terms and you flip it around so they can't see what server the requests on their API are coming from. Seems kind of fair, right?