Existing competitors (Bing, Yandex and so on) jumping in.
Massive lawsuits as Google actually sells services that would stop working, or that other vendors depend on.
Retaliation from the EU on alledged past violations.
Loss of revenue around 30-40% (just a guess) from losing EU customers (500M people market of first world countries) == lawsuits from its own US shareholders.
A wave of investments into EU newly found search market from all over the world.
Unsustainable political pressure from the US establishment to go back to EU ("we need that data and you're handing it to China or even worst, national states of Europe)
Tremendous loss of soft power and influence of the US on the old continent.
Financial default of tens of thousands of EU businesses, subsequent EU bailout, subsequent new protectionist measures over Internet businesses-
No more stupid comments on Youtube.
Who's that guy with a beard asking for money? It's Larry Page.
Websites all over EU begin to have a links section again.
Android gets banned, Nokia resurrects, with a big advertising campaign praising the long battery life and low radiation.
People cannot reach facebook anymore. They cannot look it up on Google and don't know what a domain name is. So they get on the road to ask other people how to reach facebook again. Then they become friend with them. And mate. Twenty years later Europe has now 10 competing search engines, the population had tripled as the result of mating and the average age has halved. They have far more less money than before, and they blame the greeks for that.