Version 3.0 of the ODBC connector is an alpha product as stated on the front page of the connector:

As with any other pre-production release, caution should be taken when installing this alpha release on production systems or systems with critical data. Not all of the features planned for the stable (GA) MariaDB Connector/ODBC 3.0 release are implemented yet.

Yet the installer removes the 2.0 Stable Version.

My personally opinion is that don't feel that major versions (1.0, 2.0,3.0) should replace it's prior version as it breaks ODBC connections.

However I do not expect an Alpha version of software to replace it's stable counterpart.