At least a SF weekly train from ERS (Cochin) can be started to HYD. There is high demand. I have several friends who now divert to Air Asia, SG etc since a 2 month early booking in flight gets a fare of Rs.1800/- & a person going in 3AC will strongly think about flight option with a fare difference of only Rs.300 or so.
Moreover there is high benefit to save 2 days (a working person surely needs a 2 day leave if travelling on weekday!) as Sabari starts from HYD at 11.15AM & reaches next noon at 1.20Pm to ERS!! This is a huge waste of time considering money factor if booked early.