I believe climate dictatorship will come already this century if our decarbonisation efforts stay as weak as they are. It won't be under that name though. One sufficient policy would be to price everything in money + co2 equivalent currency. Every person in a country gets a certain co2 currency budget per year. Pretty simple actually (yeah yeah, the small print will still be long but the gist is simple).

I could easily be convinced that dictatorships make a big comeback this century, however I find it unlikely that they will have a good carbon policy.