I think ketamine is niche, and it will remain so. It's one of many tools. MDMA also assists in restoring brain plasticity[0].

For me, by far the most interesting development in mental health is Chris Palmer's work, which asserts that most mental illness is primarily a metabolic issue. If you think that can't be possible, read his 2022 book[1]. Here's a podcast[2].

[0] https://www.nature.com/articles/d41586-022-02871-w [1] https://www.amazon.com/Brain-Energy-Revolutionary-Understand... [2] https://www.youtube.com/watch?v=oC-sQogfh3Q

Also check out this book Brain Energy: A Revolutionary Breakthrough in Understanding Mental Health https://www.amazon.com/Brain-Energy-Revolutionary-Understand...