I'd guess a reasonable start at delivering near-equivalent capabilities, capacity, and reliability from a standing start today, in just Europe, to be about €50b. The shopping list isn't all that tough. Who wants to pony up?
European cloud providers already exist, and companies from industries and countries where data protection is regulated are already happy clients (see Swiss FINMA, and German governments required by law to carefully respect GDPR).
Maybe an influx of business will make us grow the European clouds, but that's ok, we're up to it.