What is Square Enix expecting? Sales, lots and lots of sales. (That being said, these estimates on Square Enix's part do seem rather conservative for both titles being released — however, Yoichi Wada did state that these projections do include DQIX and FFXIII. Eidos also factors in as well, so these numbers are kinda low, no?)
Still, screw spin-offs, those guys should release big, expensive DQ and FF sequels every year!