Unfortunately the only person who can change the Guildmaster spot over to another person is the Guildmaster. There is no lack of activity clause, that I'm aware of. Honestly, unless you're particularly fond of where you are, I would find a more active guild that communicates on Line daily so that you always know what's going on. Those types of guilds have leaders that would either A.) never leave, or B.) hand off leadership before they do.