Well, it's markedly more likely and workable than having them colonize America, I'll say that much. For a POD which might eventually lead to this happening, how about having Zheng He turn East instead of West after visiting Majapahit on one of his voyages, push south-eastwards in an effort to find the source of origin for the Spice Trade, and wind up discovering Northern Australia in the process? Follow that up with Chinese merchants, traders and settlers establishing themselves there as they had in the Philippines, or possibly to an even greater extent given the lower indigenous population of the region (and the more abundant natural resources, when/if they try their hands at mining- the gold and diamonds in North-West Australia, all of that silver in Queensland, and all of that jade in New Zealand, could all be incredibly lucrative for the Chinese), and you could well wind up with 'Chinese Oceania' (in the same way that OTL's Oceania could be described as 'British Oceania').