The rumors point to a 28MP full frame sensor and a DIGIC 6+ processor, which is consistent with past rumors that referenced the camera as the 5D Mark IV.
Second, the 5D X model name is consistent with the Canon 1D X branding. The 1D series jumped from the 1D Mark IV naming scheme to simply 1D X.
Additionally, the number four is considered a bad number in Japanese culture and it is not uncommon to see that number avoided in product naming schemes. Although, recent models from Canon and Nikon have not avoided it so much.
While all of the Canon 5D Mark III talk is still rumors at this point, I appreciate readers continuing to send in these tips. As always, if you have more details, please feel free to reach out and contact me.