Why pick 2020 as your starting point? That is simply around the time the current set of techniques came about.
We had generative art back in the late 90's - my screensaver has been generative art for over 20 years now.
Obviously generative art has come a long way but people have been working on various approaches to it for at least 30 years.
Similarly, tools could fabricate podcasts years ago that sounded terrible. Now we have NotebookLM doing a "reasonable" job with two cliched-sounding "hosts". In a few years, will they potentially be able to create something akin to a professionally produced podcast given some smart prompting? The progress made so far points to yes, and I haven't seen any evidence so far to be pessimistic about it happening.
It took 30 years in the generative art world to move from cave paintings to the level that we have today because we needed new techniques.
For podcasts we are at the cave paintings level.
If we can get to professional level quality podcasts with the current techniques then we might only be a few years away.
I think it is more likely we will need new techniques which puts us potentially decades away.
If we look at LLMs the improvements over the last 18+ months since gpt4 was released have been minor despite incredible levels of investment.
Then what are you talking about, where can I get it?
Give it time. Progress is fast.