The train will roll from Chennai to Pondicherry without any passengers for 200km. The seats emptied in Chennai won't be filled up again after we leave Chennai. It'll end up similar to the Chennai Vijayawada VB, which typically stays empty on its way from Chennai to Renigunta, except on weekends. When it comes to TVL Chennai VB to madurai and Trichy, these big cities need a quicker link to Chennai, arriving early before noon and departing at 1600. Since the train starts from TVL, 2 hours are wasted roundtrip, and extending it doesn't really make sense, given the 30-40% occupancy after Madurai. If they extend it, they should start a new VB from Madurai to Chennai departing at 5:45.

A trip from Tharamani to Pondicherry should be around Rs 700, so I reckon people will start digging it. Tourists catching flights in Chennai Airport might also be game (it's like the 16115 Tirusulam stop). This one could really give the ECR route a run for its money in terms of timings compared to the current trains.

Chennai to Trichy/Madurai/Thanjavur/Nagercoil would happily welcome more fancy trains. A train with 8 coaches would totally rock on this route, no matter what time it is.