csw,
Every financial projection is "hypothetical" until it happens. Otherwise it would be called facts. Yes the S&P earnings estimates are "hypothetical" until it happens. The tax benefit is also a rough estimate. You guys are missing the point. No matter what basline number you choose to use, there is going to be a adiition to the earnings estimate. If you don't beleive that, then we are wasting time debating on that.
And i did not say P/E estimates are a good indicator of future S&P price. I merely pointed out what the S&P price would look like, when the P/E reaches overbought territory. The market can choose to stall here and collapse - nobody knows. That's crystal balling. But then just look at some of the major bull market tops and see what P/E values were acheived before the collapse started.
NAV, you asked me to believe Thompson's estimate when he himself didn't by qualifying the numbers with lots of caveats. I agree that tax cuts would add to earning and reduce price earning multiples ceteris paribus - but the world doesn't function with all else being equal. Hence my point that the benefit is likely to be far less than the full impact of tax rate reduction from 35% to 20%.