You model is totally mistaken. The T-80UD and Al-Khalid moving was made in Pakistan in answer of Arjun development in India. lighter, more numerouse tanks is the best assymmetric answer to western type of armor. They hoped India will no capability to make Arjun in enough number, and I cannot say, they were totally wrong, arent they. So India needs both Arjun and T90 for counting such assymmetric treat.
Yes.. That is a fair point . I agree that Paki option was narrowed down to numbers when the M1A2s weren't going to come through and they went for a high/low mix of T-80 and Al-Khalid (modernized legacy T-55?) , and their assumption of India not fielding Arjun in numbers played out .
And yes, you are right that the newer tanks you mentioned.. SoKo K2, Japan's Type 90, and the LeClerc are 3 man , auto loader and 6 wheel bogie machines , which tend to be lighter than the 7 bogie, 4 crew machines. The Japanese type 90 infact looks uncannily like Arjun (both of which look like Leo2).. not surprising given that the Germans were consultants to both !.
The answer to that, is 1) K2 and the Turkish next gen tanks are use a massive number of LeClerc systems and hence the LeClerc like layout and hydropenumatic stuff , autoloader etc. 2) So Ko and Japanese tanks have to be smaller, because Japan and So Ko's terrain are hilly and not really meant for desert and plains warfare.
India's tank terrain is the classic armor battlefield of vast open deserts and rolling flat plains. These kind of terrain are tailor made for large heavy armour, with standoff engagement capability and need low ground pressure to navigate sand and marshy areas in wetlands. That way, probably a 7 bogie design is needed. The 4 man crew was selected for the Arjun because back then, there was no good autoloader that was implemented (other than the T-72) and a human could outperform an autoloader in loading large single piece ammo..
Notice however that crew protection wise, the newer 3 man/auto loader tanks you mentioned are alteast a generation ahead of the T series. They have bustle mounted auto loader and ammo storage and armord ammo storage in separate blow out compartments .. T-90 continues with the "legacy" ammo storage method.
If the Army wants a 3 person tank, with a smaller weight and foot print, it will not be too difficult to do that. India can source the Merkava IV autoloader or the LeClerc Autoloader and put in either the engine it is developing (which will be successful given the huge experience Indian pvt sector has with diesel engines.. and they are tapping ig) the common rail version of the MTU engine if need be as a back up option ..(both these engines are lot more compact).. Once those are done , a decision can be made to either reduce the weight of the tank with those savings or to up armour the Arjun, keeping the weight as the same.
However, all that is for the follow up version of the Arjun, MK II.. First, they need to get the Mk1 into service in numbers after debugging it fully, establish the reliability and engineering performance of the components and then use those components or follow ons for future tanks. That is the ONLY way tank development can progress.
Importing dead end T-XX series is not the answer to either future needs or strategic imperatives for India.. Our armour needs to be dominant over the Pakis in technology, capability AND numbers. The only way to do it is to have a cutting edge tank that is locally designed and produced. Something that the Pakis and Chinis should have great difficulty matching.