> Most(?) of the 5G deployments are planned to be of this type.

I am a software researcher in the field and I do not think this is the case. Most 5G deployments for the foreseeable future will be on 3.5Ghz. I do not think mmWave (30Ghz+) has been accepted for commercial use in any country. In fact, in many roadmaps mmWave is referred to as 5G NR (new radio), which to my understanding was left for later deployments. To give you an idea why: the mmWave receivers and transmitters (at my current facility) are the size of a door. I think the problem is shrinking those doors to fit your smartphone, but then again, I do not work on the physical layer nor have much insight regarding regulations.