I wish Xbox would strike a deal with him to build his own studio from scratch, with an aim to have multiple teams. Lost Odyssey and Blue Dragon were really good, MS just needed to keep at it to build those IP up, among some others, and show commitment to Japanese-made games.
Man, I really hope he gets another chance to make something of the scale of Final Fantasy/Blue Dragon/Lost Odyssey/etc. then soon.
I have no clue what their relationship is like anymore, not sure how many of the people involved in the original deal are still at Microsoft, but injecting enough money to Mistwalker to grow in to a multi-project studio would seriously be a dream come true. They've already got an internal development studio doing all the work on Fantasian, so they've started to return to that more classic form, and every piece of their output from the 360 / Wii was great, RIP Cry On. I know people are going to say they're just a mobile studio now, and even Fantasian is a glorified iPhone game, but I encourage people to wait for its release.
Having Sakaguchi on the Xbox team would also be a great way in to the rest of the Japanese industry. People respect him, he could serve as a voice and face of Xbox in Japan helping to convince other studios to work with Xbox, even just for ports. They're making progress, but a name like his would really supercharge that. And then once there's more Japanese developers and games on Xbox, maybe they'll finally properly localize the fucking dash.