A world where you never know if you're talking to another human being unless you're right in front of them.
You wouldn't be able to trust that it's your own mother on the phone. Every thread and chat may just be you talking to yourself through a pile of code. And god knows who that code's talking to. Photo, video evidence in court? Can't prove it's not real, your honor.
An artificial world. Everyone sequestered away into their own bespoke realities, separated by unbreakable walls of uncertainty.
We currently have a relatively convincing language model, that can make a singular, somewhat convincing and vague response, but we do not have an AI that can engage in meaningful conversation. Play with ChatGPT and you will realise it still has fundamental limitations.
We are a long way away from AI being able to actually accurately replicate the human mind, and overcoming that obstacle will be decades away at least. By the time AI can convincingly replicate human conversation, it will almost certainly have motivations and independent thought - there will be many, many more implications than "you can't trust digital conversations".