I think that DC @60fps would look noticeably better than F6.
Sure. What they have in common is that they are categorized in the same genre. But they are clearly different to each other, with different intentions when it comes to colors and lighting.
But also sure, better hardware can render better graphics.
The hell, even GT6 is just superb in some graphical elements compared to racers on current-gen, and that game is on last-gen conslole.
It looks very good for a last gen game, definitely. But seriously, this also is because of lighting. The IQ in GT6 is obviously worse than "racers on current-gen" which is totally ok.
I really can't imagine what PD will do with GT7 on PS4.
Why not? Look at how races look in TV and you see what is the optimum. The only question left is how close devs get to it.