We're trying not to promise dates anymore since as you rightly noted we aren't very good at estimates. Server Components rely on Concurrent Mode for streaming, but as I mentioned in the talk, we feel pretty good about our progress there, and the remaining work on CM is mostly to simplify it and make it easier to adopt. So it's not too far ahead.

As for Suspense, Server Components largely are the evolution of Suspense (although it works on the client too). We've decided to hold back releasing Suspense a year ago because we didn't have a solution to waterfalls. Now we do. So it's all coming together. In general, a lot of what we do is research, and research has many dead ends and takes time.

I think this is easier for them to pull off than Suspense and Concurrent mode because of the difference in complexities. I'm expecting this to be mainstream by the end of next year.