Going by that logic Greek or Latin must have persisted forever (at least in Europe, or Sanskrit for that matter in India) as the link language of choice.
Because today is different. One can get from one point in the world to another in a few days at most, call anyone instantly, and trade as % of GDP is enormous. English is the world lingua franca - not one region's and so the present situation is unprecedented. I categorically said English is not special. But the order in which things happened in history matters and that English was dominant at the time that the pace of technological innovation accelerated rapidly and globalization set in is significant.
It is the difficulty of displacing English that makes Mandarin hopeless. This follows from common sense, not "Macaulaite indoctrination" (I want to laugh, but I'll leave you alone on the use of that term as this is getting rather OT as it is). Recently there was a spate of articles about China having "overtaken" India in English-speaking (along with all the alarmist panic of India losing IT edge because of it) because they've begun to encourage English at a truly massive scale. One does not see Mandarin being taken up in the rest of the world combined at such levels. Yes, Mandarin is difficult, almost prohibitively so. Young children are hard coded to pick up language (hence why feral children have lost that ability permanently), so the fact that 1.3bn people speak it is irrelevant - they grew up doing so. Learning it as an adult is a whole another ball game.
It is easy to abstract away and conclude that Mandarin will become an important language for international communication. But when you get into the specifics of it, it becomes apparent that there is simply no path for this to happen. As I said, globalization encourages a single lingua franca, not many. It's English OR Mandarin, not both (Mandarin can be second place as Prasanth said, but it will be extremely distant second place). Ironically, the Chinese seem to have less faith in the viability of their language internationally then you do, or they would not be teaching themselves English by the hundreds of millions.
"Core national identity"? This is suitable for other states, not one which has more diversity than any continent except the one it's on. I'm content with a civilizational identity and it appears most Indians are as we still exist as a single state when others with far less diversity have shattered. National identity is more analogous to the identity of the different states of India. I don't think India needs to be like other states by forcing something that doesn't naturally exist nor do we need to feel inadequate because we lack it. What works, works. There is also a great irony in your insistence on abandoning English despite its obvious economic benefits when you cite the situation of Muslims suffering economically because of their failure to use other languages for the sake of identity.
As far as Indian "overuse" of English goes, this is your personal problem. I suggest you get over it because things aren't going to change. I see no harm in it as using Hindi is no different from the PoV of a non-Hindi speaker. If you want to explain that away by pretending I have a colonial/dhimmi mindset, go right ahead as I don't care enough to bother with it (as I said, this is your personal problem). I reconciled myself to these facts long ago and I maintain that this sort of fear derives from insecurity about the strength of one's own culture or an inferiority complex. I recall that there was a thread on BR for this very topic (link language for India). You can go vent there.
Prasanth, I do not consider it racist to call the Chinese writing system primitive as writing is a technology. The alphabetic system and its cousins have wiped out, without conquest, all competing systems in almost all other parts of the world despite the ancient civilizations all having non-alphabetic systems. It is an *innovation*, superior to its predecessors and it dominated by virtue of that superiority just as India's base 10 w/ 0 number system was picked up all over the world, even in East Asia. That the Chinese don't use it is probably because they weren't exposed to it early enough. This is nothing for the Chinese to be ashamed about as it's just how things turned out and it works for them so there's no need to transit to any other system. But there's no use pretending that alphabets/abugidas/abjads are not a better system, as the fact that countless languages have abandoned their native systems for it will attest to that. One can memorize the Latin alphabet in a matter of days. Indic systems are indeed more difficult because of the compound letters but these are rarely used today (which is a good thing) and everything that is commonly used can be memorized in a short time like Latin. Obviously one needs practice to develop speed but it's outright impossible to learn the Chinese logographic system quickly for those that are not linguistic savants.
Admins are about to get angry so I will not continue with this. As I said, go to the link language thread.