A Canadian online gaming store has an estimated release date as May 27 for both the Priestess and Warlock Academy expansions, and the "Lost Grimoire volume 1" for Arena. I'd take that date with a grain of salt; for instance, I could envision the release getting delayed a couple weeks for a more spectacular release at Origins. Or it might arrive early and go on sale immediately (iirc, Domination came out ahead of the initial ETA). But in any case, we shouldn't be waiting much longer.