you math guys can plot the slope but 7,000 seems to be where history would put the Dow today. Factor in the change in economic viewpoint over the last 20 years and we still can not argue for much above 10000 and I'm not sure that argument is super strong. Knock out the last 20 years where day traders became cannon fodder for the institutional traders ( think many actually betting their house!) add a plethora of oddly envisioned products hitting the market (think one house* writing 78 Billion $US in credit default swaps) and what that did.
*think of the name of a Pirate Rum Company.