I like the way u broke it down magic. The lawn mowing scene was awesome. Especially with the sexual innuendo referenced in 'mowing the lawn'
Your analysis of the switch type casting makes perfect sense. I have been thinking they are polar opposites while you make a good case for them being one in the same.
I can see Hart becoming Cohle if Hart ever endured the kind of losses Cohle has but I can't see Cohle ever becoming Hart. Maybe Cohle was like Hart at one time but life has made him sullen and tragically existential. Cohle's character is more evolved introspectively. He is honest about his perceptions with others and with himself. He is not a slave to his insecurities and fears like Hart is because Hart still has so much to lose.
I'm enjoying the journey as well. Its an exceptional story. The tidbits of pre-internet hobby culture is also very fascinating to me. Very!