It's impossible to train on raw document > 1MB (I don't know the exact limit, but there is one). You can't vectorize weights (or can you?!) and the output context is limited. So you can't train a big model on it's previous weight or others models weights.
The output context can be "extended" using agents but I doubt anything coherent may be outputted using that technique.
It seems some level of interpretability, even if it requires tooling, could result in the ability to spin out synthetic training data sets from other models in an automated fashion.
Now that would be crazy
Now THAT would be crazy