Future shock, hydraulic discs and Di2 sound pretty sweet indeed. But personally, if I already had a 2016 Roubaix, I’d just upgrade the groupset.
I have both 6870 and 6800 and am another one of those guys who would definitely opt for an electronic groupset for his next bike. I mainly like the speed, auto-trim and not having to adjust it as the cables stretch/wear. But I’ve also experienced a couple of times where I mis-shifted due to the buttons not having enough of a tactile response.