If other orgs wanted to use the scheduling capabilities without support for w3c accounts and calendars, could that be readily supported? For example, could there be a flag to turn off some validations / error checking (e.g., group in our database, chair in our database, irc channel, registration data)?
Other orgs could still set up a github repo with session proposals (possibly using a simplified template), read them into the spreadsheet, and propose a schedule.