Varying sources including CanonRumors and Northlight Images are reporting that Canon's next full frame DSLR will be the 6D, and it will be announced in October. That, and Canon will not have a new DSLR ready to unveil for Photokina.
The next DSLR from Canon, rumored to be the 6D, is now said to be a 22 megapixel camera with a body build similar to the 7D, but with the full frame sensor on the 5D Mark III. Northlight Images has said the following on the matter:
"It's suggested that the new 'cheaper' FF camera will not appear until October and that Canon will not have a new DSLR for photokina. We're told that sales of the 5Dmk2 at its lowered price (UK ~£1500 [includes 20% tax]) and in particular, associated lens sales, are still going strong.
Trade shows such as Photokina are not so important as they once were to the big manufacturers, so I suppose 2011 cameras (1DX, C300,) the 1D C, the 5D3, the 650D and the EOS-M will make for a decent stand, particularly if you add the expected new large format printers (iPFx400), a slew of point 'n' click updates, the finally announced EF200-400, and maybe a lens or two this month."
We will keep our ear to the ground on any further rumors regarding the next DSLR from Canon.