Yup you already can specifically sequester your data to Microsoft's or Amazon's EU-only servers, and even smaller companies like 1Password offer to store your data on 1password.eu instead of 1password.com.

However there can be weirdness sometimes. I vaguely remember a case where Microsoft had to hand over EU data to a US law enforcement agency due to a court order, but giving that data would violate Irish law. I know there's a new variant of the EU-US Privacy Shield, but with the current US administration that could get ignored very easily.

Which raises the question: can for example Microsoft-the-US-entity in de jure sense cleave off Microsoft-the-EU-entity whilst still maintaining de facto connection between the two? If not, there are definitely big opportunities abound.