I never got this 12.9 iPad rumor.
Certainly, a few people might use such a big iPad (showrooms, museums...) but I don't see many use cases that would make this product sell in big numbers.
Apple is not about filling every niche, otherwise they wouldn't have retired the XServe or the 17'' laptops. They retired all these products and usually keep a tight focus on hardware lineups.
And u didn't get the iPad mini rumor either
There are needs in all sizes my friend