Developer Steve Troughton Smith has recently discovered (via 9to5Mac) that the keyboard view in iOS 9 is more adaptable compared to the current iOS keyboard. As you can see in the screenshot above, it seems as though the keyboard has been designed for larger displays in mind, thanks to it being able to show off more keys, symbols, numbers, and so on.
By displaying more keys at a glance, it reduces the need for iOS to have a third page to display additional symbols that the user might need, but of course this would require having a larger display in order to fit it, otherwise the keys might end up being too small and too cramped for smaller tablets like the iPad mini, for example.
Of course none of this actually confirms that the iPad Pro is real, but it does seem to heavily hint at that. Apple is rumored to announce the iPad Pro this fall where we can only assume it will be launched alongside Apple’s other iPad refreshes, but until then do take it with a grain of salt.