Yeah there are plenty of upcoming HQ publications for Glorantha. Take a look at the "Upcoming Glorantha publications" sticky. Out of that, as I understand it the following are all HQ-based pubs - The Eleven Lights, Notchet guidebook, Casino Town/Holy Country book, Trollpack, Riders of the Storm, Sun County (not sure about this one).
Also, although the Glorantha sourcebook is part of the 13th Age releases, it's totally system free and is basically a big book of myths.
So don't worry, there's plenty of stuff in progress for HQ:G.