Vande Bharat will be hit only in high density routes, but on other hand you should see that how much passengers will travel in this train owing to the fare.
Chennai-Mysuru is already proposed.
Chennai-Ernakulam can be done but there are already many trains running and most of the people use only night train.
Even Shatabdi Express haven't gain that much value...
more... on this route, It is used only when bus operators charge hefty amount during holidays and festivals. The actual cost of decent bus is Rs.600-700 but during festivals this goes to 1500-1700. Then Shatabdi also goes in wait list.