There is no specs of price info leaked yet for the Sony 24-105mm f/4 G, but the lens is definitely in the works. This lens will also be selling as kit lens with the new A-mount FF camera. Both products are most likely to be unveiled during Photokina 2014.
Sony’s new zoom lens 24-105mm f/4 G, covering wide-angle to telephoto focal lengths will compete against the Sigma’s already a good performer 24-105mm f/4.0 DG OS HSM lens.
Sony 24-105mm f/4 G Lens Coming With The New A99II