Will 7G be needed?
I say no for the next 15 years. Because there are 1425235 other things that are way much important than this.
So 5G for most folks is just marginally better LTE and that's about it. Any higher frequencies like 6G (30GHZ~3THz) or 7G (???) won't achieve much of anything outside of laboratory, because they will hit exactly same walls like 5G UWB.
Its extremely limited range and penetration is a benefit there because you can put up thousands of cells without them interfering with each other.
It was also meant for offices as a managed WiFi replacement. Stuff like that. In this vision every laptop would have 5G built in and could work anywhere. It just didn't take off because of the chicken egg problem. Not many phones with mmWave. Not many providers with it.
The speeds thing was just marketing BS as usual but mmWave did have benefits in niche scenarios.
It did not took off because the whole sales pitch was utter nonsense. Why would anyone put 3rd party 5G BTS inside their buildings and then pay for data, when they can use WiFi for free + they control the network so they can decide how data are shared between stations and which stations are allowed to be logged in.
I can see that 6G is pitching... exactly same thing. Which predictably is going to fail... on exactly same issue.
And it would have worked similarly to managed WiFi. Lots of companies outsource their WiFi and network. Many don't want to have that knowledge in house. Basically the provider would play the role of network outsourcing party inside the office and the outdoor connectivity would be more of a value-add.
The benefit would have been much higher speeds due to much more available bandwidth (way more than even 6Ghz WiFi), more security (people can't just poke at it with some packet injectors), less interference due to managed spectrum, higher density due to the beamforming and low penetration. Oh and it would have improved phone connectivity inside those buildings to boot. It could be combined with VPN/MPLS like connectivity so that laptops would always be behind the firewall even outdoors without having to run a VPN client.
This was also the pitch that led to those laptops with 5G built in that intel and Qualcomm were on about (Qualcomm was heavily trying to get into the laptop market back then). But it kinda stalled. I don't think it was a bad pitch though. It also came at a time when people weren't actually working in the office due to the pandemic and it lost momentum, beside the chicken and egg problem.
I could really see this taking off under the right conditions. But the whole laptop with mmWave isn't a thing anymore now. Perhaps 6G will bring a renewed push with it. Personally I don't think it's a bad pitch at all.
In india, jio is using 26ghz for wifi now instead. It's a service called airfiber. This don't even use any 5G. It's a weird custom hybrid solution where all the frames are wifi. Density here means that it's feasible to put the receiver on the rooftop of apartment buildings wherever you can get LoS. So in some sense it's been salvaged and those bands are actually being used. It's a fairly popular service.
URLL failed because it's main immediate usecase was supposed to be vehicle to vehicle comms. And auto didn't want telcos middlemanning there. But there is still hope here.