You are putting WAY too much faith in the ability of programmers. Real AI that can do the job of a therapist is decades away, at least - and then there’s the approval process, which will take years all by itself. Don’t underestimate that. AI therapy is uncharted territory, and the approval process will be lengthy, detailed, and incredibly strict.
Lastly, there’s public acceptance. Even if AI turns out to have measurably better outcomes, if people aren’t comfortable with it, statistics won’t matter. People aren’t rational. I don’t care how “good” Alexa is, or how much evidence you show me - I will never accept that a piece of software can understand what it’s like to grow up as a person. I want to talk about my issues with a flawed, fallible human, not a box plugged into the wall.
You ask a valid question, just much earlier than necessary. I’d be surprised if AI was a viable alternative by the time you retire.