Step 1. Mobile operators block Google ads unless Google pays.
Step 2. Google blocks access to gmail, YouTube, Google search, and every other Google site from all IP address ranges to those mobile operators.
It then becomes an interesting race. The EU competition regulators will say Google can't do that and threaten legal action. Meanwhile, the mobile operators' customers will be gathering torches and pitchforks...or switching in massive numbers to any operators who have not pulled this idiotic stunt.
What happens next depends on who is faster, the EU bureaucrats or the angry villagers.
