It won't sell 10m but it will still sell loads (Regardless of UK's first week - ever heard of legs? something Sony games are great at) and that is good profit for Sony since the PS3 engine for the game is already built. Unlike Capcom who will use profits from blockbuster games for mobile, Sony will take this profit and put it towards PS4 resources. It's a win win really. People who want and will buy this installment will help fund future projects of Sony games (Potentially GT7 on PS4)
PS4 doesn't need a GT to sell at launch when they are going to sell out anyways. The same reason why MS didn't put out a Halo for X1 launch. You don't put your biggest seller out on that system when your selling everything off the shelves anyways. GT is a system mover and it's better to have GT7 out for PS4 next year or the year after with a potential price cut or bundle.
