This would make it a lot easier to manage a transition between an existing Drupal site and a new WordPress site. In my case, all core programs and the existing databases are on the same server. It would sure be nice to just configure the new WP Civi to look at the old Drupal Civi database.
Most of the database table can be shared between the two sites. However, there will/might be an issue with the WP user table and the drupal user table with the civicrm_uf_match table. One potential option might be to ensure that the user ids across wordpress and drupal dont conflict, i.e. choose a high starting point for the WP user table (which is a manual process in mysql)