The thesis that the IVC language may have been related to Dravidian is dead as a dodo. Only Tamil nationalists pursue it. There's really nothing to the Elamo Dravidian hypothesis also. For a time it was pushed feverishly by a David McAlpin. The theory rested on a slender footing. Essentially there was a Dravidian affiliated language called Brahui spoken in Baluchistan by a small number which raised possibility of IVC language being Dravidian and at another remove, an Elamo Dravidian language family. But the Brahui language is now accepted by most experts as a medieval period (i.e., 1000-1600 AD) immigrant into the highlands of Baluchistan from Central India. This has basically blown the stuffing off the Dravidian hypothesis for IVC - not that it was ever very strong. The Dravidian language family, in the opinion of experts, continues to be an isolate confined to southern India.