All the above shall be a flop as the proposed shatabdies shall have
(1) poor occupancies- not much premium ac class traffic in all of the routes to justify a Shatabdi.
(2) All routes shall have very low avg speeds and operating speeds. A minimum standard regarding the standard of signalling, rails and sleeper density etc. should be there to operate a train of Shatabdi/Raj class.
(3)...
more...

Guwahati is only city which can be expected to give respectable number (but not high enough) of paxs to Shat. Even Ghy is often overstated as it has achieved its status due to old zonal HQ and representative of all NE states. Other cities are so small that a handful of paxs can be expected for a Shat. Even a full length JS shall be hardly patronised on the above routes.
(4) For Dibrugarh already daily Raj and many other trains are there
For Naharlagun- the existing guwahati naharlagun daily express is running with just 10 coaches.
Murkongselek- existing daily train from Kamakhya is running with just 13 coaches
GHY-New tinsukia already several options are there
Above shows that proposed train services are not actually required.