Honestly, I don't see overheating as a deal breaker for many users, but certainly it would be a challenge for some. It all comes down to how you're using a camera. For me, I'm firmly in the camp that is appreciative that Canon is putting out bodies and equipment and giving users access to it's full potential. I'm just happy they didn't compromise the weather sealing to enable better heat dissipation - I'd be out if that was the case.There is no documented overheating problem with these cameras...reason...no one has had one to test! Not one single production model has been tested by an independent reviewer. Stop speading unsubstantiated rumours.
With that said, on whether it does or does not overheat; Peter McKinnon is sponsored by Canon and openly said it was overheating on him if he was shooting a lot of 4k/120:
Also, Canon doesn't seem to be hiding that heat is an issue - I could be wrong but I believe Canon even released a document with recording time limits due to heat. Heat was my biggest question on announcement - I was begging for them to avoid putting in vents like in the S1H or a cinema camera! They made the right choice, for me anyway.
Frankly, in my opinion this is only a scandal because people are looking for something to point to as a failure, and reaffirm the perspective that "Canon is not looking out for their customers" or are trying to trick the world. How dare Canon not bend the rules of physics for us the consumer, how dare they not be 10 years ahead of the curve instead of 5, how dare they hide overheating by letting one of their ambassadors openly say it overheated on them in a promo, and even release a document showing the limits caused by heat. Honestly, I'd rather they put 8K in with a record limit for overheating than not have 8K at all. It shows me they're giving the user the choice.