I am not sure if you are missing this point. There is no Hindu unity. On the other hand, Hindus are united in their hatred of Muslims. If you remove the Muslims, Hindu unity will no longer exist.
My personal opinion is that this won't end until a lot of Muslim blood has been shed, regardless of who is in power. You just can't remove hate from people's hearts. There has to be a revulsion from within, and sadly, that revulsion comes only when blood has been shed (Nazis/Serbia/Rwanda)
I used to hold the view that Hindu unity is artificial. While that may be true, the fact remains that they are a front when 'facing us' (whatever that means). I am kinda reconsidering this view as well - I mean if you look at Jamaican Hindus for instance, even they stick together staunchly. So perhaps there is more to it than meets the eye. What I will not deny is that traditionally Hindu society has remained fragmented because of the inherent social stratification and apartheid system that is built into it.
Now coming to your second point, I doubt anything like that is gonna happen.
1. Nazi Germany was defeated and forced to come to an end. Modi's Hindu Rastra is an ally of major world powers. There is nobody coming to liberate us here.
2. Serbia (I think you meant Bosnia) was lucky to find NATO as its supporter. In the post Cold War period it was an opportunity that the Western Powers did not miss. There was no inherent desire to save the Muslims there - just to prevent Serbia from re-establishing a united Serbia-Bosnia aka Yogoslavia.
3. Rwanda ended simply due to arms embargoes and armed UN action. The fractures still remain on the ground.
I don't know why the Hindu, the average Hindu hates Islam or Muslims. It does not make any sense to me at all. Even when I take a step back. When I try to think rationally and not as a Muslim. Nothing comes to mind.
So I doubt there will be a revulsion in the hearts of Hindu minds when they see genocide of Muslims happening. Just check the conversion of nominal Muslims last week and see the glee on Twitter and every social media. Nobody protested. Not even the liberals uttered a word.
See. You put your religion in your constitution
India's Constitution is inherently Hindu or pro Hindu. There is no doubt about this.
Why do we still pile hate on you for being an Islamic republic?
because hypocrisy is easy.