I feel like the course has just come full-circle, like a good Seinfeld episode.

I was originally interested in this course because I had come to suspect that I needed more insight into tensor products (as they had become 'the thing that kept popping up' for me), and Prof. Baez suggested that symmetric monoidal categories and the like would provide an even more sophisticated way to think about tensor products.

And now we've landed squarely back at vector spaces, but with a vast 'back-story.' I don't know that the course will have much more to say about braided monoidal categories (as the word 'braid' seems to only appear in Spivak's book in the references), but I feel like that's where I should head next, when I'm ready.