I speak Chinese at home, and took Chinese SL in year 11. I imagine that if I had done Chinese SLA, though, I would have done much worse. The distinction between SL and SLA essentially recognises that some students, who perhaps attended Chinese speaking schools, had greater opportunity to learn a language than other students. The new suggested changes to the system are simply the same logic applied to two other groups, those with a background in Chinese, and those without a background, so I think the proposals definitely have some merit to them.
However, I don't know if it would be best to merely dump all the native speakers into SLA, as you're adding one level of distinction, but removing another which exists for a reason. The difference between an native SL student and an SLA is student is being able to have a conversation on the weather and being able to write an essay on global warming. Grouping them together would essentially give you the same sort of problem - a group of language students finding it difficult to compete with another group of students with greater opportunity to learn the language. I suppose that it would encourage non-native speakers to take up the language, and reward them more aptly for their efforts, but it seems to me that it will punish middle band of Chinese native speakers, who speak the language too well to do Chinese SL, but not well enough to do well in SLA. It seems to be discouraging people who can speak Chinese quite well from taking the subject.
I guess the other issue is that, if speaking Chinese at home puts you into a different category than others, would speaking English at home put you in a different category from those who don't? I know people who, from a young age, only spoke Chinese at home, and as a result had difficulty learning English. While they were immersed in an English-speaking school environment, many struggled with the subject well into high school, resulting from their lack of exposure to the language as children. Yet, many students from such backgrounds also go on to learn English very well, and as a result it would be very difficult and perhaps arbitrary to be streaming students based on their exposure to the language.
I think it comes down to encouraging non-native speakers to take Chinese. The changes to the system would make it perhaps more accessible to non-native students, while making it more difficult for some native speakers to compete, and as a native speaker, albeit one completely done with Chinese, it's always going to feel a bit unfair having the scales tipped against us, when it is already quite difficult to do well in Chinese SL. But at the same time, I can see that the overall aim of the change is to increase enrollment in the subject of Chinese, as it is likely to be a very useful skill in times ahead.
I'm actually divided on the issue, but if the changes actually do go ahead, I'll be glad I did Chinese in 2012, haha.