The 13" Macbook Pro with retina display is proof enough that Apple will waste no time switching to ARM for Macs. They simply care about other laptop qualities a lot more than about total horsepower. If it's just "good enough" or even slightly underwhelming in terms of performance, it doesn't mean they will not do it.
You draw that conclusion because of the video performance? I'm not following. The CPU performance wasn't even mentioned in the article. Is it a step backward from the 13" MBP?
According to Apple both variants of the 13" MBP use the same CPUs - either a 2.5GHz i5 or a 2.9GHz i7 - so I imagine the CPU performance is identical between the two. Of course, there might be a bit of a CPU hit for apps having to deal with the retina display, but I suspect that the GPU plays more of a role there.
