http://www.sonyalpharumors.com/sr2-first-very-wild-rumors-abotu-the-april-23-products-a-mount-and-rx/It's not a rumour from a known or reliable source, but, if true, this would probably rank among the dumbest things Sony has done.
Sony's success in digital photography doesn't rest with its A-mount, but with its E-mount. The full-frame A-mounts were not a success, especially among professional users - Sony just doesn't have the lens lineup to back it up, nor do they have the demonstrated long-term commitment to photography to persuade people to sell their Canon and Nikon systems to move to Sony. The E-mount, however, allows them to easily poach users from other systems - and, with the A7r especially (and, to a lesser extent, the A7s), they have done so even among professional shooters with significant investments in other systems.
A new, high-resolution, full-frame A-mount won't win over anyone, due to the requirement to invest in an entirely new lens system and due to the limited range of the lineup. A new E-mount would be much more likely to be a success and to cause Canon some pain, particularly with regards to sales of the 5Ds.