Why would my browser that is used to display static HTML need high performance 3D rendering or a low level assembly target?

The websites that use LLMs don't exist yet. Think of something like meetup.com. Instead of that you ask your LLM for something to do this weekend. It finds events, other people looking for something to do, and you have an ad hoc meetup.

Beyond that it's like looking at a blackberry and predicting what it'll be used for in the future. Hard to say "oh gay men will use that for casual hookups and it'll be called Grindr".