S&P500 - R59, ever since i read some of the indepth reporting about the Panama Papers, and now the Paradise Papers (e.g., see Wikipedia articles on both leaks), it's clear to me that there is YUGE, HUMONGOUS WEALTH sitting on the sidelines, trillions of dollars (or dollar equivalents) of wealth, and, funneled through various channels, i think that is going to keep the markets going strong for some time.
Even if there is a severe market pullback or correction or even a bear market at some point due to a horrible natural catastrophe (think: California and the "Big One" earthquake and all of southern Calif. or northern Calif. in ruins), i think that hidden Huge Money will sooner or later swoop in and create an impressive V-shaped recovery. Just like it did from Fall 2008 onward and each of the few corrections and dozen or so minor pullbacks since then.