P/E ratios are not going to drop until some kind of socialist revolution reverses the movement of money from the budgets of people who spend it to the bank accounts of people who invest it. When control over dollars shifts from people who want goods and services to people who want capital assets, the price of a capital asset (P) must go up as demand rises even while the price of what it manufactures (E) goes down.

Ever hear "there are no alternatives to stocks?" The alternative to stocks in the past was consumption; not so when concentrations of wealth cannot be spent in a thousand lifetimes. It's the perfect storm for crazy P/E. If you believe Piketty's work, that kind of reverse shift never happens gradually, and these P/E ratios represent the "maturity" of a period of relative peace and stability.

It's worth mentioning, as an aside, that as long as inflation is positive, investors do not actually need to see earnings.