Are most Devices we use Now going to be Non Compatible with the 5 G Networks???

To Be FRANK. . I am not for 5G. We do not need it.

If it is true that 5G will be 100 times faster then 4G networks then we will benefit from that speed and the things we can accomplish with the speed in terms of downloading. It wouldn't take long to download and synchronise the entire blockchain if those speeds would be supported.
But I am not sure that it will benefit bitcoin in terms of better adoption just because it becomes so much faster.

There will be a huge demand of 5G because of VR. Virtual Reality demands huge bandwidths. AR will also push it up.

5G can't be good or evil.
The faster the internet connection the better.Blockchain has other issues to be solved.
Quantum computers can be real threat to the blockchain(in the distant future),higher internet speed is not a threat.

Afaik , cable or wired internet is more faster and stable than wirless signals like 3g/4g/5g/  .  5g would be more beneficial to us internet users because we can now download and stream a little more faster than we have right now on 4g networks  but 5g is not really beneficial on crypto use because it cannot speed up the transaction because the transaction speed will only depend on the fee's  you put up .

I heard there is an ongoing debate about the possible benefits and problems that are associated (or will be associated) with the coming introduction of the 5G technology. Some are questioning its viability and whether we really need this new introduction and some or many can be wondering what can it do for them today and into the future. I am then hoping that soon things will get clearer and at the end of the day the technology can be useful in many ways and that any backlash or negative side-effects can be manageable so we will not be wasting out time and resources here. I am personally for the improving of the speed of all internet connections most especially here in the many third world countries where service providers have specialized more on attractive advertising of their services rather than improving what they are offering.

The speed of 5G might be advantage but otherwise I think this will make the ness.Many device at the moment are not compatible to use 5G  but I guess there will be some time to adapt. Regarding Bitcoin, I don't know if there will be some benefits become in essence Bitcoin doesn't require such high speed.

another point that people are missing when it comes to internet speed is that it sometimes doesn't really matter how fast YOU can DOWNLOAD when you are being limited by the upload speed of the nodes that you are connecting to. they can either be limited by their internet speed or they can manually limit their upload speed to save on their monthly traffic cap and their costs.

Cryptocurrency, Bitcoin, 5G, no one can say 5G is evil or vice versa,
The world of technology predictions for now there is no certainty that something is accurate, this is the same as 5G against Bitcoin.
well, from that As you say, good predictions or suspicion based on what you know at this time is natural, in alertness, to your Bitcoin assets.
This is the same as what happened to 3G, 4G, you definitely know about marketing for 5G.