The latest I’ve heard about the 5D Mark III’s sensor, and it comes from multiple places. Is we’re going to see it remain in the neighbourhood of 21mp. I’ve been told both 21mp or 22mp from various people.
Announcement? The most consistent mention is March for an announcement. I think they’ll announce a 5D mark III type camera after the February 7, 2012 announcement of the Nikon D800.
4K EOS Camera The announced development of a 4K Canon EOS DSLR could make some specs that come out hard to decipher. I believe a high megapixel EOS body is coming. The question is whether it would be the 5D3 or the new 4K DSLR.