Yeah, I think the "human intervention required" step suggested by GA isn't very scalable.

How about:

1. Upgrades: New version gets promoted to extras-testing whilst there is already one there: its votes get halfed and any super-votes required removed.
2. Demotion: If an app requires X votes to promote from extras-testing to extras, receiving -kX votes will demote it from extras-testing to extras-devel. (Where k could be 1, I dunno).