A commoner, one from masses from India would don the mantle of Kalki Avatar. An avatar could only come from India from where flows the wisdom of Bhagavad Gita and Upanishads (independent spiritual treatises). There was nothing more pure world over than teachings of Lord Krishna in Bhagavad Gita, prime reason why oaths in Indian courts is taken on Bhagavad Gita.
Mounted with power of Bhagavad Gita and Upanishads, this one-man army, the awaited Kalki Avatar needs re-establishing Dharma (righteousness)! Evil cannot prevail much longer. The dark forces of Kali Yuga have to be annihilated in totality.
As ordained in scriptures advent of a messiah, savior avatar is only at the opportune moment, never before. It is most likely that Kalki Avatar surfaces only after the start of world war 3, a truly man-made catastrophic calamity. Even during the world war and aftermath the ailing society would need a soothing balm to assuage the hurt feelings of those who were innocent but remained indifferent.
It is primarily the indifferent attitude of so-called innocents that results in advent of an Avatar. People who could have taken care of themselves failed to react to the evil forces in time. With no solution in sight as ordained by God advents an avatar. Kalki Avatar would prove nemesis for evil mongers only. He would have nothing to do with so-called innocents (called akarmanya in Hindi).