With MPEG-4 in place, external storage just over the horizon, and the Ethernet port waiting for VoIP, I don't see E* rushing to replace the 622. They just need to get it back to the stability level that it had before.
A majority of users think that the current software is more stable than the earlier software:
http://www.dbstalk.com/poll.php?do=showresults&pollid=1775