Nobody really knows. It would seem to me that if it were something relatively simple and inexpensive, they'd have already done it.
However the EPA was allowing a partial fix, allowing for a significant reduction in NOx levels, but even that may be difficult.
Mine will not be receiving any "fix" unless it is proven to work without any issues. Right now I will most likely just install a DPF delete, retune the car, and motor on. It needs a DPF anyways (which is why I was able to get it cheap). But since it is missing a pedal, it isn't the ideal car for me to keep. I already have several buyers for it once a DPF delete/software is installed should I choose to sell it.
Really wanting a Sportwagon with a manual. I have one here now, but it has a pano roof which makes me want to punch kittens and I am not sure I will be able to beat Volkswagen's offer on this car, and there isn't anything "wrong" with it so it isn't like I can score it on the cheap anyway.
Have another Sportwagon I am thinking about that is essentially brand new at only 27k miles. It too has a pano roof, though.