I think the resources Microsoft has invested in the Japanese market could've been better spent elsewhere, and I don't think they'll focus on Japan as much next gen as they did earlier this gen. Despite all their efforts, they've made little headway in the region, and in reality they don't really need the Japanese market.
At this point they have enough brand power and marketshare in the West to convince any Japanese developers of note to work on 360 if they're also working on ps3. Look at FFXIII. SE felt compelled to work on a 360 port JUST for the West, ignoring the 360 in Japan entirely.
Square Enix, Capcom, Konami, and the rest are all fully on board the Microsoft train for the time being, and this has nothing to do with the amount of consoles Microsoft has managed to sell in Japan. Given the amount of time and money Microsoft has put into marketing, price incentives (I wouldn't be surprised if they lose money on each 360 sold in Japan, given how little they go for), and buying timed exclusives (Tales) or making publishing deals (Blue Dragon), this money most likely could've been more effectively used in increasing marketshare in the West, through even better marketing and paying for more exclusives that cater to Western demographics.







