[alexro]

That's what versioning is for, isn't it? You still can submit old data under the previous version, and old apps will works just fine as they won't see the new data.

New apps will have to deal with old versions somehow, or some back-end job will produce new data out of the old.

[matc]

If you change the schema then the old version of the app can break. For example, if two tables are merged together.

If one suggests old data and new data be stored separately then the door to data inconsistency opens.