Fantastic read. The OP does a great job of describing how gradual progress occurs in mathematics. Thank you for sharing this on HN.

Deep down, I'm still hoping someone or something will find a beautiful proof that is more elegant than brute-force counting and verifying that four colors suffice for all unavoidable configurations that reduce to all other possible configurations. According to the article, there are 633 of those configurations. No idea if a more elegant proof is possible, but I hope it is.