That figure seems a bit confused.

Up until the final categories, it seems more like it is attempting to delineate time periods sourcing that dominant flavor of scifi, not the time period postulated in its fiction. It lists the contemporary topics influencing that fiction.

But, it then goes wrong as it wavers and transitions into future time periods.

Sticking to the writers' eras, it is the listed "cassette futurism" period that is really cyberpunk. That's where it was born, influenced by those technologies, dystopian ideas, and noir aesthetics. By the 90s, we were into post-cyberpunk works like Snowcrash, reacting with parody and snarky absurdity.

I not sure I agree, and read it it is an attempt to map the source material influencing the writing, not the writers eras at all. Steampunk particularly doesn't make sense as a map to writers eras.

At any rate, I understand the confusion now. As you note Cyberpunk proper was having it's obituary written, in some ways, in very early 90s, and the core of it was written well previous to that. So 1990-2000 doesn't fit well as either writers timeline or (in a handwavey sense) technology timeline.

I may be showing my ignorance, but I think those like Verne and even Shelley were the original steampunk authors. I don't think of it as a totally separate genre as people continue to try to recapture and riff on the same styles and set pieces almost two centuries later. It is born of that era.

Similarly, I think you could still write new cyberpunk. It's not dead, but on hiatus.

Well most of them had a sort of "sideways" technology, better in some ways but worse in others (not unlike how a lot of 1950s SF had people on starships fiddling with slide rules). Cyberpunk generally posited human-level AI and near-realistic VR, but generally didn't feature mobile phones (payphones were common) and presumably analog TV ("The sky above the port was the color of television tuned to a dead channel" implying analog static).