I will recommend against this idea. And here is why (at a higher level of abstraction)
1. This means the cloud services aren't reliable in the first place. That itself is a big problem. Else with reliability guarantees and multi-region/zone it should be pretty safe to stay in one place.
2. Devil is in the details. None of the current cloud providers behave in a similar manner of operation. Maintenance will become a nightmare.
3. Setting up security and addition/removal of nodes will be tough if not irritating. 
4. Huge cost involved in data transfer across different platforms if not inherent delay in replication as well.
5. Potential risk of getting into chase situation amounting up to node failure due to network delays.