Cyberpunk 2020, as fun as it is, is really showing it's age. Cellphone modems the size of bricks in the game when players to the table and turn off their smart phones? Showing off 80's glam models when I have to pause in the middle of the game beyond some guy is blasting electronically made dubstep down the street? etc...
As much as I hate to say it, Shadowrun has my players attention. It has wireless, it has social media, it has an easier transition between Meat world and the Net. It has elements that is directly relevant and thus can more easily Identify with vs keeping stuff in the 80 retro future and keeping it there. For a game that includes Dragons and Magic for god sakes, it handles technological issues that are much more relevant to my players that I can pull with 2020.
Cyberpunk is back in the mainstream. Smart-Targeting guns are mainstream news, drones waging warfare is a hot topic, and more but it needs to be updated with the technology and issues of today otherwise you risk missing the boat.
Well about technology, it's really easy to fix.
My Cyberpunk 2020's game take place in the "present" world
(2040, but the setting is somewhat like now), just take the global background and fix the holes, just like electric car, cheap cellphones, hacking
(i use a reworked version of the network in solo of fortune, it's way easier for you to run the game, as for the netrunner which just have to launch a few dice once it's his turns and that's all), as for the look, I'd say, replace your glam-rock boy by ravers, modern gangs, etc... like this:
They're already more hyped when it's about playing a dirty punk with a mohawk from the combat zone than a rockerboy with a mulet, don't be affraid to be drity.
You just need to find a close example from nowaday, people doesn't listen to New Wave, but to Dubstep, so just tell them "well, a Rockerboy, can be anything from a Bill Clinton to Skrillex" and that's it lol.
Sure a new edition with all of this as a "plug and play" would be cool, no need to waste time making your whole world based on Cyberpunk 2020
(and that's what CDPR is doing with CP77 it seems), but social media, internet, drones, smart targeting guns, wireless, etc is already in Cyberpunk 2020, sure not in the exact form we know now
(like the screamsheet being received by fax, just replace fax by "newsletter" or "facebook page" and here you go.).
I don't really see what's so "retro" in Cyberpunk 2020, yes, if you just take the book as it is, you'll think
"will i have to play a guy with a mullet?", but IMO It's to the GM to make some work of it's own to fix some technology stuff, and that's not so much of a stretch, since almost everything is already written in the rules, you just need to update what is there depending on what you need, for a drone I'd make it hella hard to shoot, having a few guns and a really light armor
(since it would be made with a somewhat armored plastic of some sort), smart gun are already here, etc...
Forgot the cheesy side, and just take the rules and the overall background and use your imagination, it's really easy to make your updated version of it so your player'll have some connexion with it.
On the Shadowrun side, I think you can't really compare both, Cyberpunk has one edition with a handfull of side-books to create the universe (not directly related to RT, so the canon can go really wrong sometime) when Shadowrun had a lot of official books, etc...
If Cyberpunk 2020 had as much popularity than Shadowrun I think we'd had a lot of edition with updated content, but even if Cyberpunk is quite old now, the rules are "soft" enought to be stretched around to your needs.