While Nikon's Z6 and Z7 have stolen the headlines recently, not much has been heard from Canon. However, that doesn't mean they're not planning anything, as it looks like they'll be updating two of their best lenses soon.
The EF 400mm f/2.8L IS II USM and EF 600mm f/4L IS II USM lenses are two of Canon's best pieces of equipment and are the workhorses of many sports and wildlife photographers. It looks like they'll likely be replaced by Mark III versions before Photokina, according to a report by Canon Rumors. Both lenses are as near to optically pristine as almost any photographer could desire, so it's likely any new version would focus more so on reducing their hefty weights, particularly given the remarkably light (by comparison) weight of the new Sony FE 400mm f/2.8 GM OSS lens. There's no doubt that sports and wildlife photographers, who have to lug these behemoth lenses long distances, would appreciate such reductions. Both have image stabilizers rated for four stops, so it's unlikely we'll see major leaps there, though new lens coatings may appear and Canon's new whiter paint color will likely appear on both models.