IR doesn't have 75 new routes for Vande Bharat trains, it is not feasible, there aren't many routes that can support both Shatabdi and VB running back to back. IR will most probably replace every Shatabdi with a new VB and introduce a reverse VB also in that route, so a current fleet of 22 pairs of Shatabdi will get replaced and those 22 routes will also get a reverse VB making a total number of 44 pairs Vande Bharat trains in IR, now the headache is the remaining 30 new routes which can be tried some of which are
NDLS-GKP
HWH-PNBE...
more...
HWH-BSB
BSB-NDLS (reverse)
ST/ADI-PUNE
BPL-LKO
LKO-PPTA (via BSB or via GKP)
SC-SBC
MAO-CSMT
TVC-MAO
MAS-VSKP
MAS-CBE
MAS-ERS
BBS-R
JP-NDLS
INDB-NDLS
INDB-NGP etc