"heading south for there to be a bear market".....no they don't. Prices can move sideways in conjunction with a loss in purchasing power of the currency they are held in. Indeed they could even go up ,but if they go up at a slower rate than the value of the currency goes down then the net result would still be a loss of value.
Let me say I have little time for Pratner 😉 ,but if you look at the general index levels 5/6 years ago and look where they are today and assume (as he must do) that the assets were held through the interim then in fact investors are actually now poorer in SOME asset groups in the US inparticular.
Interestingly I wonder what the loss as been in say the US$ since 1995 compared with the move in property prices over the same period (and let's not be pedantic let's leave inflation out of it on the basis it's probably adjusted for anyway by the currency value)
Hope you take my points as this is a big issue really that underpins Pensions amongst other things. It's all about timeframes and longrun values.