Unlike regular 3A coaches, Garib Rath coaches have Side middle berth and therefore increased capacity. Thats one of the reasons why GR fares are lower, because the economy works out better with increased capacity at a slight loss of comfort of course. The production of these as mentioned by other bloggers, is stopped. If a train has to be started with conventional coaches now(ICF or LHB coaches), it cant be a GR coz it would have to charge regular 3A fares owing to lesser capacity compared to GR coaches. So no more GR rakes, cant use ICF/LHB coaches, so unlikely for such a train to start!