Epistemic status: This is a thought I had since a while. I never discussed it with anyone in detail; a brief conversation could convince me otherwise.
According to recent reports there seem to be some barriers to continued scaling. We don't know what exactly is going on, but it seems like scaling up base models doesn't bring as much new capability as people hope.
However, I think probably they're still in some way scaling the wrong thing: The model learns to predict a static dataset on the internet; however, what it needs to do later is to interact with users and the world. For performing well in such a task, the model needs to understand the consequences of its actions, which means modeling interventional distributions P(X | do(A)) instead of static data P(X | Y). This is related to causal confusion as an argument against the scaling hypothesis.
This viewpoint suggests that if big labs figure out how to predict observations in an online-way by ongoing interactions of the models with users / the world, then this should drive further progress. It's possible that labs are already doing this, but I'm not aware of it, and so I guess they haven't yet fully figured out how to do that.
What triggered me writing this is that there is a new paper on scaling law for world modeling that's about exactly what I'm talking about here.