Well, war elephants would definitely be cool, but its not necessary. I'm just saying, what if this species existed throughout northern India, with a fair population? And what if they could be domesticated as easily or easier than their counterparts?
Even then, I don't think much would change- as I said, the law of diminishing returns kicks in. I doubt a huge elephant can really do
that much more labour compared to a normal Indian elephant in terms of the fodder they'll need. Camels provide far more bang for your buck as draft animals.
And yes, they would be a bit more useful in war than Indian elephants but all in all elephants are still highly overrated as war beasts.
Thus, effectively we get a very large elephant. There's just not much more that can be done with it that can't already be done with Indian elephants.
Sunsurf: Inducing musth in an elephant would be a
very bad idea. Yes, they'd become enraged killers- trouble is that they'd start by killing the people nearest to them i.e. the men riding them.