Proving Aryan Invasion or even Migration Theory is correct serves different purposes for different groups -
For Congress it is a matter of secularism. Congress since 1947 and even before Independence when it served as a controlled opposition, tried to create an 'Indian identity' that is exclusive of Hinduism and Dharma. Proving that Aryans cam from outside somehow justifies and gives a pass to rapacious barbaric Moslems. It serves as a foundation of the belief that Indian Civilization was 'upgraded'.
Leftists can use it target the unifying cause that Dharma serves. Proving Dharma as something foreign and the property of 'upper castes' helps them to further ethno-religious conflicts and create a state of anarchy. Also, given that Leftists are cucked by Islamists, it gives Islam a secular pass.
Draavidianism was a movement created by British stooges like Naicker, Ambedkar and Phule. It was solely used to further a divide and rule agenda. I don't see Draavidianism doing well in the future. A Draavid utopia would resemble Zimbabwe.