Tim Cook also said 'late next year' and unless he means Apple's FY, that's a way past Spring. I'm also of the opinion that they wouldn't just release something with fan guards because they've had a long time to do that. So, perhaps something went right with the manufacturing process this time and they can be early.
Actually, he said "later next year, not "late next year." At any rate that is all semantics, and it wouldn't be the first time Apple hedged a release time frame to manage expectations and then released earlier than expected for "bonus points." Apple needs a few of those right now, especially with the pro market that is becoming increasingly skeptical and bitter at Apple's neglect of them.