This is a little bit old, but wondering if library evolution not being backward compatible is still true.
the docs mentioned here suggest it should be backwards compatible.
Such libraries must be both backwards-compatible, meaning that existing clients should continue to work even when the library is updated, and forwards-compatible, meaning that future clients will be able run using the current version of the library. In simple terms:
Last year's apps should work with this year's library.
Next year's apps should work with this year's library.