It's specifically because Akamai wants to preserve its reputation amongst enterprise customers paying $$$ that it's giving such a big delay. And I can predict it won't be enough for many.
No doubt there be a lot of companies who don't finish until nearly the end. Barring legal reasons, I'm guessing there will actually be an extension because enough corps won't be ready at that point. Also would expect Akamai to offer extended support beyond that date (for a significant cost) on a customer by customer basis.