Xiaomi was a part of the Android One program and release their first phone under that program which was the Xiaomi A1. The phone was a hit and everyone that get the phone was really happy that Xiaomi has considered to go stock, rather than using their MIUI skin. Looks like they realized the success of a stock Android phone and will be releasing another Android One phone under the Redmi brand.
This information comes from the CEO of Xiaomi, Lei Jen, who said that they have plans to make more Android One devices even under the Redmi name. This is a good strategy for the company as Google initially made the Android One platform as a slimmed-down OS mainly targeted at the Indian market and the Xiaomi brand is very popular over there.