In this context 'a curiosity' means an oddity or peculiarity, so the author is saying that the traditional methods of psychoanalysis such as emphasizing repression, free association, and dream analysis, may be no longer needed due to the recent developments in biochemistry. Therefore, in future, these methods may seem like an outdated oddity.

The author uses words not often seen in juxtaposition. Yes, I believe the author means that advances in biochemistry are providing more accurate analyses, rendering psychoanalysis moot, in the writer's opinion.