I've read your points and thank you for contributing to the discussion.
However I'd like to respond this way:
-1st point: I don't mean it's necessarily a bad idea but that it will be very hard to implement in practice. Switzerland we studied has many languages but French and German (and maybe Italian and English (for work)) are pretty much it and while I'm no language expert it's safe to assume the difference between French and German is lesser than the difference between English and Chinese. In Malaysia the 'minorities' usually know English, Malay and their 'mother tongue' but how well can they speak/write/read all 3? I don't know, you decide.
-my 2nd point doesn't necessarily require that we marginalise other regions/cultures/connections: and that isn't what happens in practice anyway. Singapore is attractive to Asia because we try to understand all of them. Especially South Asia. In other words, learning Chinese language and culture doesn't necessarily require diminishing other cultures. I'm pretty sure our Indians trade/interact with India and our muslims with the Arabic world (in addition to South East Asia).
As to the third point I'm not sure if non-Chinese are actually banned from SAP schools because there are actually non-Chinese in SAP schools. Unlike the other main languages here like Tamil and Malay, Chinese language really requires a lot more time to teach well - but I don't think this should be a major policy issue anyway. People can learn whatever language they want and spend however much time they want but it is a fact that (especially from a English as first language perspective) Chinese is harder and requires more effort, especially when we don't have the HK advantage of true bilingualism in government and media.
Besides it isn't just SAP schools, muslims have madrasahs.
-as to the 4th point, to make my point even more clear - when everyone in the world becomes the same more or less by appearance/colour then you can't really practice racism. Right? because the 'minority' wouldn't exist anymore; neither would the 'majority.
but my final point is that people are gonna discriminate anyway because that is inherent in society. e.g. what school you went to, what grades you got, how 'beautiful/handsome' you are, how much money you make, what job you do, and a whole lot more of other stuff that we might not even know about yet but could be a possible basis for discrimination in the future.