When is the next big convention/show...???
The next big show is the WPPI Trade Show in Las Vegas and opens on Feb.20th. There are zero hints currently, that Canon will be introducing any un-announced camera's there. http://www.pdnonline.com has a link. This may indicate problems in the development of the next generation of professional cameras or Canon may just wish to surprise everyone who attends.
The WPPI Convention will bring thousands of Studio and Wedding Photographers to study the latest techniques and will display the latest equipment, Imaging Services and soft wear to the Trade. The largest Dealers will be there also. Why Canon is not ready to showcase the 5Dx and 7Dx to many of their Professional customers from around the World is anybody's guess. Nikon will be there and will probably have the new D800 on display.
Follow the CANON RUMORS web site if you'd like an better idea of what is coming and when.