Although it's mentioned in
RPGamer's news report that he may come back in the future, for the moment, Nobuo Uematsu is unfortunately leaving Square Enix.
The reason for his leaving is for greener pastures, although at the time it is not clear which pastures he feels are greener, and why. It is mentioned, however, that he has quite a busy schedule, especially with his band The Black Mages.
After working with Square Enix for 20 years, Uematsu noted that his most memorable composition is Eyes on Me, the main theme from FFVIII, and that his favourite game compositions were from FFVI, FFVII and FFVIII.
EDIT: Sometime after my posting this, RPGamer ammended their news post to say that this is a RUMOUR. So while it's possible, as of now, this piece of news has not been completely verified.
EDIT #2: It has now been confirmed that the above is true. Uematsu will be joining a company called "Smile Please" in November, and does not wish to call his leaving quitting, as that term is too extreme.
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I was a little taken aback when I saw this piece of news, though the man has put in 20 years already with Squeenix. He did do the music for FFXII, so we'll have that at least.