I don't think they count as "corpses" if they're active enough to be on the front page. And cyclic doesn't really stop threads from being on the front page a lot of the time, if O.A.T.'s perpetual front page presence is any indication.
I don't think having a lot of serials on the front page is necessarily a bad thing. Seeing activity stimulates activity.
A lot of the most successful threads on /chat/ tend to be leisurely paced threads that last a really long time and always tend to be on the front page anyway. Like Chewy's music thread.