Mirv is almost there , remember agni 1 anti airfield warhead .
Well there are atleast two more ICBM in development (name not specified , except few calling nsurya and agni 6 ) ,but they have heavy throwaway weight and much more compact deriving from k4 and a1p
This was a user trial so hence the regular deployed design.
We have all seen the slide presentation with the MIRV concept by now I am sure.....fairing and all.
Compact stubby ICBM ecosystem will definitely be priority given that is where the focus must lie (to assure maximum return on deterrence from investment i.e underwater SLBM driven)....rather than going for larger bulkier bigger + heavy missiles (given setting of our priorities).
I would say Agni V is volumetrically the high water mark needed as is.....it can reach 10k km range or more with relevant variants....doing volume calc of even solid fuel energy imparted....vis a vis its contemporaries.
Agni III (which later led to Agni V) when I first saw it I already knew this is volumetrically more than enough to work with to evolve all the variants needed. It was marked change from the pencil missile agnis before it.