It seems like GPT-4 is going to be coming out soon and, so I've heard, it will be awesome. Now, we don't know anything about its architecture or its size or how it was trained. If it were only trained on text (about 3.2 T tokens) in an optimal manner, then it would be about 2.5X the size of Chinchilla i.e. the size of GPT-3. So to be larger than GPT-3, it would need to be multi-modal, which could present some interesting capabilities.
So it is time to ask that question again: what's the least impressive thing that GPT-4 won't be able to do? State your assumptions to be clear i.e. a text and image generating GPT-4 in the style of X with size Y can't do Z.
Above 99% certainty:
Run inference in reasonable latency (e.g. < 1 second for text completion) on a typical home gaming computer (i.e. one with a single high-powered GPU).
Sigh. Even this one may have fallen depending on how you evaluate llama 7b performance. Like under 1 second for how many tokens?