Kalki Avatar already exists on mother earth in India but would surface only at the opportune moment. The advent of an avatar is always for a very specific reason, re-establishing Dharma (righteousness) against all odds.
Well above 50 years of age this one-man army Kalki Avatar is loaded with jnana wisdom of Bhagavad Gita and Upanishads (independent spiritual treatises) to the extent that he shall instantly develop a dedicated following of 2000 million people worldwide.
The ruthless crusader of truth (the white horse represents power of truth exercised by Kalki Avatar) shall not only succeed re-establishing Dharma but also bringing forth a Satyuga, the much awaited golden period. A monumental change in the thinking of mankind would be seen.
In a Kali Yuga is 95% people had worldly thinking dominated by a bloated ego, in a Satyuga the position reverses. About 95% people become more inclined towards inherent spiritual values. In the aftermath of world war 3 people would prefer indulging in spirituality to reach state of enlightenment. The goal of life of all would drastically change from material to spiritual.
What is astonishing is, people remaining same only the perception changes. 95% people engaged in material pursuits of life switchover to purely spiritual values wanting to indulge in Bhagavad Gita and Upanishads more and more. As everything contained in Bhagavad Gita was universal in nature, it was never an attempt by Hinduism to promote itself.