Concern yes - but I really don't think Australia, or a lot of other countries, will go to war with China over Taiwan - most don't even recognise it as a sperate country officially
It'll belief the Indian take-over of Goa, the Moroccan takeover of the Spanish Sahara or the Indonesian takeover of East Timor and Irian Jaya. Lots of tut-tutting and maybe even sanctions but war? No way......