Regarding whether or not the TSE is overvalued.

The question revolves around the future direction of inflation and interest rates, and predictably:

1) If inflation is going up, then interest rates are going up... and the market will go sharply down;

2) If inflation is stable, then interest rates will be stable, and the market will rise from here, but at roughly the rate of inflation plus four percent;

3) If deflation takes hold, then interest rates will be going down, and the market will skyrocket, then MAY plummet. 

The difference between the latter scenario and the Great Depression of the thirties is that a great deal of expendable workforce is already out of work due to computers and robots, a trend which will continue anyways. The market in this scenario will rise strongly because of the relative rate of return between bonds and equities. It may plummet because war usually results.