Apple's upstream supply chain is expected to start supplying components for the upcoming 12.9-inch iPad in late-September and the device is expected to become available in the market after mid-November; however, Apple is rather cautious about placing related orders and the initial shipment volume is much lower than most market watchers' expectations, according to sources from the upstream supply chain.
Personally I still thinks that such a huge iPad need to be something more than just a larger iPad. Such a huge iPad will not be comfortable to hold, too heavy and too big. So it will need to be docked to a keyboard case or something to be able to use it. And then you could rather buy the new 12-inch MacBook because it is practically the same thing.
And personally I've a hard time seeing Apple doing such a thing. It would be a mistake and not what the iPad need. So I think it will be a new kind of device. It could for example run OS X El Capitan when docked to a new kind of surface that is based on Force Touch. So you have both a virtual keyboard and a virtual touchpad that uses force touch on this new flat surface. I've been doing videos about this because Apple has some patents of such an iPad dock. And when you remove the device from the dock it will switch over to run iOS.
That could be one possibility. I have some other ideas of what this device could be. It could be Apple's first ARM-based MacBook for example. It could be a completely new device. I really hope it's not just a larger iPad and nothing else, because that is really not what the iPad need to be successful again.