I think I understand, thank you for correcting me.
NP, I just sent you a PM 
My question is, what happens if (your CPU Speed) and (The total CPU Speed in the System) double in 4 years?
If both doubles then the ratio will stay the same, so the generation will stay the same. You see, it's all relative. Practically, of course, what will probably happen is that your ratio will be much less since more people will hear about Bitcoin (also given the recent surge in capitalist-anarchists and communists).