Germany introduced a similar law over a year ago, some german news organisations want 11% of Googles world wide gross sales as compensation! They also argue that Google isn't allowed to delist them because of its market power. Theire chance to win this are probably almost zero but they will use that to get a better law next time.
These newspapers sales on-paper are dropping alarmingly. They're looking at this as a way to monetize their online versions.
What has already happened: A major spanish social link aggregator (a-la-digg) is boicotting these newspapers.
What will happen: Google will remove them from the index. They'll lose exposure, and therefore make even less.