In the long run, it doesn't matter much how any of us here might imagine the "optimal end-game" might look like.  Reality doesn't care what we might think, but it does care about economics.  If pool mining is the most efficient way of doing things, then it is here to stay and will dominate forevermore.  But it's not the most efficient way of doing things, because pool mining must charge fees to cover group expenses as well as the risk of a fraudulent exploit of the system.  So pool mining will only appeal to those willing to lose those small amounts for non-economic reasons.  Even if pools dominate in the future, their continuing existence depends on satisfying their contributers, and so they really don't have any more control over the system than anyone else.  For as soon as the contributers get a credible report that they are being used to manipulate the network, or for any other underhanded activity, those contributers will simply stop contributing.  Some will mine alone, some will join other pools, and some will simply quit; but the power available to a pool operator will drop to zero shortly after it is misused only once.

I can't foresee myself joining any pool, ever.  Mostly because; if a malicious computer geek wanted to steal the bitcoin wallet.dat files from a lot of people all at once, how would he build up his target group?  Answer: start or steal a pool, and your target demographic will simply tell you who they are.