Sure it can, The newly introduced PNBE-CST Suvidha too comes with a diesel loco all the way upto IGP
Only due to the Hancock bridge it gets a WCAM-3 loco for IGP-CST-IGP run
.
Not sure what's the hesitation in allocating a ET/BSL WAP-4 or even KYN WCAM-3 loco to these trains till ET...