The Tesla-doubters have been saying for a very long time that Tesla should be worried about traditional car makers getting serious about all electric vehicles.
But the offerings from traditional car makers have kind of sucked. The only advantage they can claim is dealer-service infrastructure and general build-quality. When you compare range, performance, efficiency, and even price, though, Tesla remains a pretty clear choice.
The Hummer EV might not do it as eloquently (efficiently) as Tesla, but they claim to have great range and capability. And perceptions aside, GMC knows how to build high-end, luxury SUV's and Pickups. This is in their wheelhouse.
So I can see people deciding to buy the Hummer EV. Maybe not the same people that are considering the Cybertruck, but still a lot of people.
For me. . . if I was going to spend $100+K, I might pick the Hummer over the CT. In the more "middle" range models, I expect I would decide the Cybertruck is the better buy.