Would be nice to see Red Hat Directory Server as a drop-in replacement for Active Directory. There are several challenges to overcome in this respect, but there are now very many organisations that have consolidated on a single authentication method - Active Directory. Historically it has been several steps ahead of RHDS and other LDAP implementations.
The challenge is to improve these areas enough and implement the required functionallity to provide RHDS as a drop-in replacement. Removing AD from organisations would be a huge publicity boost for Red Hat. Windows desktops would remain, but be oblivious to their new master.