I think Polaris is just using up old stocks until they can get new material moving. I'd heard somewhere that there was only enough stock to produce another 200 or 300 bikes (which is way more than they can sell in a year, I think).
I agree with the earlier comment that a new Chief with an Inline Four would be awesome, however, development of a new engine and drivetrain from scratch is a daunting and expensive task. Polaris did it before in with Victory, so if anyone can, they can, but There's going to be a run of bikes with the old PowerPlus engine for a while. I do not think you'll ever see a Victory engine in the Indian, despite the fact that the Victory powerplant is technically superior.
Indian is all about a unique and exclusive identity...Polaris knows that and won't screw it up by cross-pollinating recognizable parts.