A similar Green Age in FR would be gods leaving Faerun, after having lost the world due to the brown tide and the halfling civilization. People might still revere them, but they answer to no call. Instead, psionics begin to develop rapidly, and more embrace this new power. In addition, Ao decides to tie arcane magic with the land itself, giving rise to defiling magic, that would be found by Rajaat, centuries later.
Of course, with no divine powers, the clergy collapses. The few remaining clerics choose the four elements as their patron deities, after realizing that the primordial do grant them with powers.
As for wizards, unable to cast a single spell, they become extinct rather soon. Or, they could have never existed in the first place, themselves being replaced by great psionicists (Elminster, the master of the mind).