Most problem with current approach, to grow abilities, need to add more neurons, but this is not just energy consuming, but also knowledge consuming, mean, at GPT-4 level all text sources of humanity already exhausted and model become essentially overfitted. So looks like multi-modal models appear not because so good, but because they could learn on additional sources (audio/video).
I seen few approaches to overcome problem of overfitting, but as I understand not exist universal solution.
For example, tried approach to create from current texts some synthetic training data, but this idea is limited by definition.
So, current LLMs appear to hit dead end, and researchers now trying to find exit from this dead end. I believe, nearest years somebody will invent some universal solution (probably, complex of approaches) or suggest another architecture, and progress of AI will continue.