How can we use I-Ching to divine politics?

Answer in Quora

Originally the I Ching was written as a book about divination in general, later versions were written oriented towards the social and military. 
Obviously, language and visions of the I Ching are located in the circumstances of thousands of years ago; so, what is really important is to learn the energetic meanings of bigrams and trigrams, because that's where everything else comes from.
If we understand well their different meanings and combinations, we will not need to resort to any further interpretation: we will see directly in action those energies in everyday circumstances.

How would Maitreya actually come back and get a message out?

In fact, it has already come ;)

Buddha Gautama's prediction that Maitreya would come when the Buddhism taught by him would no longer exist, has been fulfilled with the advent of Jiddu Krishnamurti.

The teachings of Krishnamurti are the blossoming of Buddhism. Gautama also predicted that his doctrine would be subject to degeneration, but not so the Buddhism that would be taught by Maitreya.

But while this is the main factor (the continuity and perfection of the teachings of the Buddha) there are others: the story of Krishnamurti is perfect from every point of view, going through the esoteric, scientific and astrological.

And also as it happened with the teachings of the Buddha, it will probably take about 200 years before there is an explosion of Krishnamurti's teachings.

Truth has its own rhythm.