That's not just rumors. In the interview, Craig Federighi said: > I’d say longer than six months ago. But I think we designed ourselves into a bit of a thermal corner, if you will. We designed a system that we thought with the kind of GPUs that at the time we thought we needed, and that we thought we could well serve with a two GPU architecture… that that was the thermal limit we needed, or the thermal capacity we needed. But workloads didn’t materialize to fit that as broadly as we hoped.

https://techcrunch.com/2017/04/06/transcript-phil-schiller-c...