I've heard the same advice from this forum year after year: if you study physics have a backup plan because you most likely will not become a tenured physics professor. With the growing number of physics degrees being given and the dwindling faculty slots, this makes a lot of sense. In fact, I'm witnessing its validity first-hand by my PhD application being rejected by every university I applied to for the second year in a row (and no, I did not apply only to schools out of my reach). I've accepted that it's too late for me, but will it be the same for my children? In future generations will it still be a complete and utter crapshoot to be employed as an academic? Will it become easier or more difficult? This is all speculation, but in physics, predicting the future given the present is the whole game.