Indian immigrants all over the world may come to form a powerful block, as they have slowly been doing in the US, but that doesn't mean India itself will become a strong country. It could mean that the the world has better relations with India - in the same way that Jewish elites in the West facilitated Western relations with Israel - but that doesn't mean India will dominate, any more than it means Israel dominates.
Having said all that, I've always believed that Indians are rather clever in how they pursue geopolitics. Rather than a hard confrontation with the West, like China and Russia are doing, India is basically selling the West promises of democratic friendship and market access, all the while putting its immigrants in key positions of influence and power. It's like the West is being strangled from the inside - not being able to sanction or ban India for fear of losing a key "ally" against China, yet being forced to watch as Indian immigrants take more and more control of their companies and politics.
It's almost like India is the yin to China's yang, in that sense. Of course, it's only able to pull this off because there is the threat of China that has the West begging for India's friendship, but regardless, it works. And while China shouldn't be particularly happy about it, I think it'd do well to understand and learn from what India's doing, because it represents a different approach to global power and one that may, in fact, prove to be very effective.