Don’t know if there will be any Horde Earthen-only guilds (the Horde side is after all smaller, and Earthen-only guilds will be a small niche interest I’m guessing), but it would be nice if there were some.
However, in case there won’t be any, the Stoneforge Clan is currently planning to allow Horde Earthen to join, and I’m sure there will be other Dwarf guilds on the Alliance as well that will welcome their kin / ancestors, whether they be part of the Horde of Alliance!