The Tata-Allp can be easily diverted via Chaibasa...the same route taken by Tata-VSKP weekly. Only one major station will be affected which is CKP. From Rou onwards DHN-Allp will in any case continue till Allp.
Few years ago remember one ac coach attendant saying that there was a proposal to separate both : DHN-Allp will continue as it is with more coches added and Tata-Allp will be extended till KCVL/TVC with route being either via KGP or else same route of Tata-VSKP. The biggest issue that time is absence of washing lines in Tata and also availability of rakes