Yes i agree with you......i feel that ASN-SDAH INTERCITY can be easily extended till DHN, because this is not overcrowded as AGNIVEENA EXP. Also dhn will get a good connectivity to kolkata also....Around 3 to 4 yrs back SER wanted to extend this train to PRR for 2nd connectivity route to KOAA. But ER refused strongly to this.
I think u can tweet to DRM DHN, GM ECR about this because IRTTC meeting is going on in MUMBAI today. All new trains fate is on 20 to 22 or 23 feb 2018 meeting.