There is a long pending demand to have a train in reverse Jan Shatabdi slot. Only long distance trains serve this sector in the morning ex - HWH and in the afternoon ex - PNBE. If this VBE is introduced in the already proposed slot, I would term it as a missed opportunity for IR.
As for PNBE - RNC VB, it is not required IMO. An ICE via - GAYA, HZBN, BRKA, Mesra would do wonders. When Tilaiya - Koderma section is complete, a new train with Vistadome could be...
more... introduced between PNBE/RJPB - RNC via - Rajgir, Koderma, Hazaribagh Town.