Of the 18 county captains all are 30 or over. Of those, 4 are overseas players (Madsen, Klinger, Sarwan and Chris Rogers). Of the remaining 14, 9 are England discards (Collingwood, Foster, Key, Chapple, Read, Trescothick, Batty, Joyce and Troughton).
That leaves 5 guys all over 30 and overlooked by England to this point - Jimmy Adams, Peters, Mitchell, Gale and Wallace (and even he's Welsh).
Therefore, if England are looking for an alternative to Cook from the county circuit they'll be wasting their time.
When was the last time an England captain had experience of captaining their County?
I would imagine Graham Gooch. The chances of this happening in the future appear to be receding as less and less County cricket is played by England players on central contracts.