I think is too early to say. Once the games are out we are going to see Japanese reactions to the console.
Now with that being said, with the way Sony has being acting with the PS4 in Japan (launching way later than everywhere else, not having actual important games for the market) I'm led to believe that Sony actually foresaw the decline in the japanese console market and decided to focus on the western market.
So yes, I too believe that POSSIBLY Sony is going to end up behind Nintendo this generation in Japan, and POSSIBLY they won't really care.