If everyone indexes (they won't) and that causes the market to become opaque and inefficient (that's debatable), there will be plenty of money to be made in act

If everyone indexes (they won't) and that causes the market to become opaque and inefficient (that's debatable), there will be plenty of money to be made in active investing. Once people notice that and start making money, many others will follow, and eventually the market will become so efficient that it will once again make sense to index. So it seems to be a self-solving problem, and an equilibrium.