I was just about to write that. Was there anything like take existing at that time or did he project the trends and adding a good dose of Japanese pop culture weirdness, completely on his own?
Anonymous-type groups posing in 3d avatars comes to mind.
I remembered that at the time,I found it implausible that it was possible to go online in Neuromancer without connecting to a fiber or something and that it was just handwaved away. He was right and I was wrong, it was not important.