I guess there aren't enough questions per day to graduate -- see http://area51.stackexchange.com/proposals/45110/buddhism --  there are currently 4 per day, and SE might prefer 10.

The last I read though, many months ago, was that SE no longer has a "graduate or die" policy for beta sites: i.e. a site that doesn't graduate can stay in beta for as long as it remains useful.