The last person who succeeded in reaching state of enlightenment on mother earth was Ramana Maharshi. Now we are in 2018. It is just not possible for Kalki Avatar to have a live guru like Maharshi Ramana. In present times learned spiritual gurus are difficult to come by.
The guru of Kalki avatar has to be his soul atman, the spirit existing in his heart. Allegorically Lord Krishna is our soul atman, consciousness existing in heart. If we can crush our ego in totality then voice of Lord Krishna coming from within can become our guide in the spiritual journey of life.
This is the same case that happened with Arjuna. As Lord Krishna is soul atman existing in body, it was in the battle of Mahabharata when facing Kauravas, Arjuna reached peak of spiritual life. He was able to crush his ego and out flowed sermon of Bhagavad Gita from Lord Krishna within.
Without going into details whether the battle of Mahabharata occurred or not, whether Lord Krishna existed in physical life, we must realize the philosophy behind indulgence in spirituality. A spiritual journey is necessitated for people desirous of reaching God in their lifetime. When we were truthful and also had no ego, we could distinctly hear dictates of Lord Krishna coming from within. Instead of searching for a guru externally, we must look forward to Lord Krishna within.