Looking at one of the other big franchises as a comparison. (I picked MGS) none of it's games sold over 1million in Japan (correct me if I'm wrong) all seemed to be roughly 800k including MGS4 on the PS3. So the trend seemed to continue regardless of install base.
Final Fantasy 9, 10 and 12 all sold roughly 2.8m. So yeah, I feel that FFv13 selling over 1m in Japan is a no brainer.
Edit: I'm sure atleast half of the FF fans in japan will be buying this "spin off" which I think looks better than 13 : )








