If your email were hosted on a public blockchain, Google could not kick you off.
- Decentralized file hosting for all the emails using IPFS instead of Google's servers
- Decentralized login using ENS / Ethereum Name Service instead of Google's login
- a UI on top of your data, plus an outbound server for relaying to/from non-blockchain email accounts
Overall, you end up with portable data thanks to IPFS, and a login through ENS to whatever UI you want to use/pay for.
This seems like a win to me. Haven't seen anything yet that pulls this together but the pieces are there. Maybe someone here wants to prototype it.