Low sales figures may be the best for the series in the long run in a perverse kind of way, what we have seen from GT6 shows that there needs to be a bit of a shake up. If the game bombs then it may act as the catalyst for PD to make some changes and make a better next gen for all of us.
Thing is they will attribute it to ps4 launch or Forza 5 or its a bad time of the year. And so on