Are you sure about Nirbhay's range? I mean the tested range. The longest duration flight time achieved is 1hour 10 minutes with Russian engine, since it's a subsonic missile it might have covered just over 1000 kilometres. If I am not wrong ,in all other successful test missile has flown below 700 km range.In theory they should fit the same VLS.
Length: 6 m
Diameter: 0.52 m
Weight: 1.5 tons
Brahmos Block III
Length: 8.4 m
Diameter: 0.6 m
Weight: 3 tons
And targeted specs of Brahmos NG
Length: 5.4 m (3m less than Block III)
Diameter: ?? (should be less than Block III)
Weight: 1.5 tons (50% of Block III)
Remember the Brahmos NG specs we know is from the time when India was outside the MTCR. The range of the NG was kept limited to 290km then. That may not be the case anymore. Also Nirbhay project is now closed & in its place we are going to get the ITCM. Who knows what size that is going to have.
Nirbhay's 1500km range seemed alright for 2013, when it began testing. Now we have a Brahmos variant that may go up to that range. Many of the global peers of the Nirbhay missile have significantly greater range, we need to keep pace here. May be instead of bringing the Brahmos down to Nirbhay's size we should do the opposite. Make the ITCM as big as Brahmos Block III, like the Russian Kalibr missile. That should increase the range by 500 km at least.
I even doubtful about the project success too. Since it's our baby we are hesitant to call it's a failed project, more than 50% test flights were ended up as failures and out of the successful test none of the test has involved full 1500km range firing, even the latest test which involves indigenous engine too ended up in failure, remember that was the first test involving an indigenous engine inside Nirbhay . Glad that they shelved this project and moved to New missile design.