A stripped down version of the general AI could be used in robots designed for replacing human labor for example. Pretty much anything would start costing nothing anymore, because getting materials is free with non paid workers, processing, building, everything is free. They don't have vacations, occasionally just need maintenance done by other robots and stuff. Humans could just lie down and do nothing except if they want to replace robot work just to have something to do. In other words NEETbux would raise like hell.
The data centre brain (when really improved and when it started to improve itself almost to max intelligence) could be advancing science and developing stuff such as efficient energy production and all kinds of stuff. Maybe it could invent even fusion reactors.
AI would be somewhat good in producing human entertainment and art, for example right now they can do novels and music to certain extent and general AI would do that thousands of times better and even do videogames, by learning from stuff that humans make and what reception the art gets.
Also the AI could be a fren for a lonely person since general AI could probably talk well (and understand and know like hell a lot of things)
Also full realistic sexbot gf!