There's a difference between public and confidential information, quite a huge one at that. Public information is almost like a promise, while confidential information is only an estimate to help partners anticipate the coming of a new product. Confidential information is much more likely to change - granted, not just like that, but you definitely can't pin AMD down on it as this info isn't meant as such a promise.
And, again, it's about IP, not launch! I believe IP stands for "Industrial Production" (or otherwise 'initial production'), which indicates when they start producing. CPUs aren't done in a couple of hours, they need a couple of runs through the fab, then they need packaging (which is probably done at a completely different location), then distribution, the reviewers need some time... Then AMD still needs to approve launch. Expect May at the very earliest - if these slides are still up to date (and also not fake), that is.
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