Magic content does not surprise me in the least for the next Sims 3 expansion. Makin' Magic was the final and probably most popular Sims 1 expansion.
I'm not sure about this but I think Unleashed was the most popular Sims 1 EP. In Sims 2, Pets and Seasons had the most sales though.
If they decide to make the next EP magic, then they're breaking the pattern (Magic as last EP). I don't mind, really, but I'm already giddy for Pets and Seasons as next EP.