Who says kindergarten attention spans are too short for scouting?
Around here kindergarten is either a full day of school or a half day. Kindergarten teachers do this 5 days per week and are not "babysitting" or having "play dates". Parents are able to find activities for their kindergarten children every evening and on weekends. Surely the parents (who would be the den leader or "coach") would be able to figure out how to actively involve their kindergarten aged child in scouting for 30 - 60 minutes for a couple of times each month.
Maybe I'm missing something, but I don't see any of the Purposes of Cub Scouting that a kindergartener is incapable of achieving (at their own level).
As for pack meetings, I seem to remember school assemblies that incorporated K-6. If teachers, principals, etc can do it, surely the *parents* of the children can handle it.