With increasing stray cattle population will it not be wise to popularize bufallo as the primary milk producing animal in India, at least?

I would say no for replacing cow with buffalo as the main dairy animal. Because there are a number of reasons like- less preference for milk consumption than cows, less overall milk nutritive value, more fat % (obesity & other health issues), tropical climate leads to summer infertility/sterility, hard milker etc.
It is also approved by the world’s most of the food administrations/ organisations that cow milk is the best in overall nutrition component.
But actual thing is that we must go out of myths & social taboos regarding cattle rearing. Also, we must formulate policies accordingly.