McAfee is a different matter and the mobile market could have been won but not in the way that Intel hoped.
When answering take into account that Intel's fab services division couldn't really compete with TSMC (at least on price) .
What is relevant is the ability to compute within a power envelope. Intel didn't try to scale down its new designs for mobile. It tried to scale up old cores with new technology - something that they got good at during the tick-tock development flow. And guess what, new core designs beat process improvement. Intel eventually reached same power envelopes as ARM with more computing power, and better overall performance due to better memory bus access. But it reaches them after 8-12 months after Qualcomm does, so it's a full generation behind in terms of mobile development.
Specific to this acquisition, Movidius packs 150 Gflops under 4W of power. Skylake packs 100Gflops under 120W of power. The difference here is more than 2 degrees of magnitude. Moving the designs to the new Intel processes should cover another significant improvement. So that's what's going on.
Where did you get the measurements? Link please.
M2 to Skylake is like apples to oranges. The RISC cores are based on Leon, and then you have 12 SHAVEs/VLIW cores, which are very good at number crunching and GPU/DSP-like tasks, but they are not really general purpose CPUs as such. I think you should exclude them from your comparison.
Anyway, good for Movidius, I wish 'em all the best.
Intel i960
Intel i860
Itanium
Added: Intel created a huge moat and wall around their x86 architecture. It worked very well for them in keeping out the rest of the world. The problem is, they inadvertently bricked up their gate and burned their drawbridge and now they are imprisoned in their own castle.
Already the cheap end x86 notebooks were ditching i3 for atom, and being "good enough".