You also have to consider the platform as well.
The GPU is incredibly useful, though it lacks one key ability. If the chip manufacturers can work out a way of doing random access textures so we can treat them as RAM, then the CPU suddenly becomes far less important.
Physics chips exist, if they become more common then that's one less thing for the CPU to worry about.
The slowest part of a game, is game dependant. If you are doing a beautiful 3D landscape with soft shadows, light rays, and all the other toys, then that's were the most t states are going to be used.
If you are doing a simple sprite game, but with complicated physics, then the physics engine is going to burn the most t states.
If you are doing a board game, like chess, then the AI is going to burn t states like charcoal at the superbowl car park.
The key to the problem is looking at the game design and working out where the bottleneck will be, then spending a lot of time coming up with a good design for that part of the game.
Then finish the game (god, three words that represent something that most people just cannot do ) and if it's still running slow, profile.
Profiling is so important and often shows problems that you didn't even consider. For instance in C# the garbage collector is rubbish, if you create a lot of garbage then your game will stutter.