THR indicated that the move resulted from a recent meeting between Johnson and DC CCO Geoff Johns.
Johnson confirmed that he was playing Black Adam in 2014 (see “The Rock To Play 'Black Adam' In 'Shazam' Movie”), but THR reports that he has been attached since 2008. In that time, Johnson has helped revive the Fast & Furious and G.I. Joe franchises, led Disney’s Moana to the top of the box office (see “'Moana's' Turkey Day Triumph--Another Win for Disney”), and generally put a bankable shine on anything he’s starred in.
Given Johnson’s verifiable star power, New Line and DC doubled down on Shazam, bumping Black Adam from supporting character in one tentpole to starring character in his own film. The new film reportedly mirrors Johns’ comics version of the character, an antihero who battles enemies who would enslave his people.
No further details on writer or director for the Black Adam movie were announced.