Euthanasia over psychiatric conditions is already a very real thing in Belgium [0] (and the Netherlands I believe). Swiss seems to be more conservative in approvals all across the board but mental isn't off the table either [1].

[0] https://bmjopen.bmj.com/content/5/7/e007454

[1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6794705/