Hi guys. I am seriously considering upgrading to 5D Mk4 and have been casually researching it for months. While getting serious about my plan, I came across a thread on DPreview today about several 5D Mk IV bodies having been inexplicably bricked. I would link the thread here but wasn't sure whether POTN frowns on the practice. Google should find it for you. The impacted owners noticed no prior symptoms from their cameras and after 10-20K+ trouble-free clicks, the camera would suddenly die and be completely unresponsive to any battery, OEM or not, regardless of its level of charge. A few people even had the problem recur on their repaired cameras while several have had their cameras with Canon for weeks now (as of the last page of that thread).
If this has been discussed here, feel free to point me in that direction. Curious on your feedback. Every new piece of equipment is bound to have a few problems (the overheating issue with my 7Dc comes to mind), but I don't recall anything quite this catastrophic happening to the EOS DSLR series. For someone who doesn't shoot that frequently, a usage-based issue like this won't occur until after the 12-month Canon warranty expires, which gives me pause.