In ER my guess would be for HWH-RNC Shatabdi conversion and a HWH-BSB VB via Gaya. Or if IR is adamant on only introducing new trains and not converting existing Shatabdis then a HWH-NJP VB on morning slot would be great imo. Though HWH-RNC VB doesn't look much feasible to me as even the current HWH-RNC Shatabdi is not having a great occupancy. Even HWH-PNBE is questionable with majority of passengers preferring non ac travel.