There's also something called Moore's law. Meaning, we have exponential growth because we don't know a lot about a subject at first, but then that starts to plateau the more we know about it. Translations, and AI are very likely subject to this just as much as computers, and performances. So, while we might expect it to get better, determining how much it might get better is the difficult part.
Eventually, once enough AIs spam the internet, they'll mostly get data from other AIs instead of humans as input. By then the internet will be one big circle jerk of AIs trying to impress eachother, and us mortals move on to something else.