The $20/mo plan is not the goal, that's not even close to sustainable, that's basically just a charge to verify someone is human. The goal is you reduce that 25m to 20m and you charge 1/5th of a SWE salary, let's says it's 100k and you replace 5m with AI agents @ 20% that's 100 billion, and that's just one industry. It's also one of the more difficult to replace because software engineers are actually much closer to artist than engineers.
It's the actual engineers, lawyers, marketers, medical professionals and accountants that are the real targets.
There is a lot of focus on AI assisting software development right now because they are the people most willing to use it. AI as it is now will probably create more SWE positions overall. What you will have is software designers being added by AI and it's domain knowledge to build applications that replace the other professional roles.
The cost to utilize AI is going to be much much more expensive as it is heavily subsidized right now.