Are LLMs at a practical limit for layer stacking? [D]

Can LLMs stack more layers than the largest ones currently have, or is it bottlenecked? Is it because the gradients can’t propagate properly to the beginning of the network? Because inference would be to slow?

If anyone could provide a paper that talks about layer stacking scaling I would love to read it!

inference layer llms love machinelearning network paper practical scaling stack talks