There are no, nor will there ever be, plans for an Indian faction in ROTR. The first thing you have to learn when it comes to discussing the ROTR universe is that present day real life preconceptions
do not apply. This is due to the fact that the ROTR story considers itself a sequel to the original Generals/Zero Hour, which already had a completely
unbelievable storyline involving hypercompetent crypto-Islamic terrorists that humiliate the US, destroy Europe and get defeated in Germany of all places by China. Any notion of geopolitical realism has thus fallen out of the window even
before the actual ROTR story involving a resurgent Russia and a militaristic alliance of European states. As such, any notions of India having the potential to being a future great power in real life cannot be applied to the ROTR universe and you can only discuss it within the internal logic of this fictional setting, not 'because in real life'.
That said, we have accounted for India's role in this fictitious, fantastical world, which you can read up on
here. The short version: Pakistan suffered massively during the war against the GLA and initiated a new peace and reconciliation process with India because the GLA was a massive threat to
both of them. This resulted in the creation of a Bangalore Pact, a cooperation between Pakistan and India, wherein the two former rivals stood together in a mutual effort against the GLA, which led to the restoration of Pakistan's own territorial integrity, a peaceful resolution to the Kashmir conflict, as well as forming a bulwark of independent states against Chinese domination of South Asia. We also learn that much of the Indian military in the mid 2040s consists of imported hardware from Russia, including the famous Sentinel tank. Beyond that, both India and Pakistan are also members of the Commonwealth, which has become more important and connected during the collapse of the European Union after the events of Zero Hour, so much so that Indian and Pakistani volunteers came to the aid of Britain during WW3, as can be read
here. All this considered, we can say that India in the ROTR setting is an important regional power, with a strong economy, and its most notable achievement is in the fact that it is now in a peaceful coexistence with Pakistan. However, it neither has the geostrategic need nor the political will to be a global superpower, so it cannot be placed in the top tier military category of this world alongside America, China, Russia and Europe which have interests and alliances that go far beyond their immediate 'neighbourhood'.
In gameplay terms, India will also not be added as a sixth faction because there is no distinct gameplay that an Indian faction could provide. The thing with designing factions is not 'this thing exists in real life, so we could add their military vehicles X, Y and Z to make them a faction'. The first thing you need when designing a faction is an answer to the question as to what it does for the player. What is their playstyle, what makes them unique, what are their special mechanics? It is only after you have nailed that down, that you can do the second step and ask 'okay, so what country/organisation would this faction represent, what makes sense in the setting, what gives you a distinct stylistic flavour? For ROTR, we already have five distinct faction styles covered and they represent the most powerful entities in this fictional world: High-tech Americans, defensive Europeans, steamrolling Russians, Chinese horde tactics and hypercompetent terrorists. There is no clear potential for a sixth faction that readily presents itself, so there is no potential for India, same as there is none for Japan, Korea, Israel, Persia or any of the other countries/local powers of the ROTR universe.