I really couldn't see it happening as a public toll bridge any time in the near future. While the Mid-Bay Bridge has been very successful, Bo's Bridge (Garcon Point Bridge near Gulf Breeze) has had some real problems meeting bond payments and the Emerald Coast Bridge authority that is supposed to be solving some Ft. Walton Beach traffic problems is currently on about its fifth different incarnation in twenty years and has only a big finaicial hole and eight different feasibility studies to show for its efforts. St. Joe or no, I can't see another bridge authority getting green-lighted in the Panhandle right now.
Much more likely that St. Joe gets sick of waiting for some sort of approval from Tallahassee and goes the private route, IMO.