re: Avoiding Cloud Lock-In
You will be hard pushed to get a vendor to cover the migration cost to another cloud provider, but what you should expect is that the cloud vendor enables you to extract your data in an open and usable format in full and at no or little cost and little effort. Also you should ask at what point you can extract the data, how often and if this facility is available up to and past the contract expiry. Many cloud vendors have an exit clause of 30 or 90 day notification and only allow data extraction up until contract expiry. Ideally you want one that has no contract notice period and gives a grace period after contract expiry for still being able to export your own data.