Would be great, and I don't see why they technically can't do it, but I don't think it's available. I guess they thought that even the 6S+ screen size isn't enough to do what they would like it to do.
Of course, what will probably happen is that in 11.5 months, Phil Schiller will announce it as a game changing feature of the iPhone 7 and miraculously forget for 20 minutes that the iPad is a thing.