While I do think there's going to be a huge market for cloud-based LLM serving, the fact that consumer hardware can run close to SOTA models fairly easily (e.g. high-RAM MBP config), seems to me that the provider market won't be as big as investors are betting on.

Most of the rewards will be reaped by consumers rather than providers.

We're also in an age where the current levels of RAM in consumer devices were almost entirely optimized for prior to the existence of LLMs. I find it highly likely vendors will optimize for higher RAM capacity over other priorities in future hardware.

How long until a 256GB RAM laptop (shared with GPU) is reasonably cheap/available? I give it a few years at most.

It's possible that models grow orders of magnitude larger, but I find it more likely that the size of models will grow along the curve of cost of training decreasing/hardware cost improvements. There will be a sweet spot where it's economical to train larger models, and private companies won't push much beyond that.