Hi Xue An,
Thank you for your question. From what it seems based on your description at least, I would think that there is no urgent need to extract the shaky tooth at this moment, as it is the baby tooth that is exfoliating naturally. It should not hinder the eruption of the adult tooth.
We may not be able to tell if your child needs braces at this time, as there are many factors in place that determines that. For example, jaw growth of both the upper and lower jaws and their relativity to each other, the size of the teeth when t the arch size etc etc.
As such, I recommend bringing him to see a dentist from young, such that any issues can be addressed early, and early interventive treatment, if any, can be rendered.
Hope this helps!(:
