system
Given the following post, respond as if you're commenting on Reddit:
human
CMV: mm-wave 5G is impressive technology that is not, and probably will not be, useful for cellphone use

The title should tell all. My position is that 5G on millimeter-wavelengths is a super cool technology that may have several uses in the future. I don't know where (cars seem the most likely to me), but probably somewhere.

What I'm pretty sure is that mm-wave 5G is not useful for smartphone use, nor is it likely to be useful in the future. I have two main reasons for this.

1. mm-wave signal can easily be blocked, to the point where the only way to have a sustained 5G signal is to be, at all times, at most a couple 10 meters away from a transmitter. Even then, the signal will often be blocked by trivial things like trees being in the way. Basically, unless you have a direct eye-contact with a transmitter that is relatively close by, the chances of a 5G signal getting through to the phone are minimal.
2. Mid band 5G can transmit far more data than is required for any cellphone use, and there is no technology on the horizon that would require more than the 400Mbits per second that mid band 5G can already offer (enough to carry 16 streams, all in 4K). In fact, the 400Mbits is far far far more than any cellphone use needs at the moment, and is therefore more than likely future proof for several years.

The way I see it, for mm-wave 5G to be useful, several things must happen:

1. An infrastructure must be built to provide reliable mmWave signal at least in major cities. This would require the construction of at least several thousand transmission towers in all cities, which while possible, is difficult in the near future.
2. Cellphone use must change so that mid band 5G speeds are not enough any more. This is unlikely because 1) net speeds currently far outpace the processing power of the phones and 2) the most prominent data guzzler, video streaming, is already capable of providing 4K video (more than most phones can display) and is unlikely to continue to grow exponentially.
3. Most importantly, the points above must happen **soon,** that is, before some alternative to mmWave is proposed.

I don't see how the three points above could all come true.
gpt
This is essentially the "people will never use cars because there are no paved roads and horses are faster" argument. Millimeter wave technology wouldn't be useful *now* where the infrastructure just doesn't exist and the software side hasn't caught up, but once this new bandwidth is available within cities (especially along dense thoroughfares and in high capacity venues like concert halls and sports arenas) the applications will catch up. 

If anything, we should just be excited with what people will be able to do with this. Instant high quality video download would be slick of course, but we will probably get far cooler things like amazingly responsive wireless AR and the like.