I'm not sure you can blame a business (or country!) for killing other businesses.
It is purely you and me, the buyers, that decide who will and who won't survive, not manufacturers or importers of Chinese trailers. Doesn't matter whether the Chinese import salesman convinces a gumby to buy a $3k trailer with a 3 month warranty, if the schmuck buying it thinks it's a better deal than a $20k camper with a 2 year warranty, it is a good deal. Over time if people come to realise the imports are rubbish and stop buying them, the sellers of these things will go the way of O'Briens et al.
People whinge all the time about the Woolies and Coles monopoly but I see way more people shopping at those places than I do in the local bakery & butcher. Guess who's going to survive.
Chinese imports simply offer an alternative to Aussie made (i.e. expensive) campers. It's us that will make or break a business - if a business doesn't have a product I want at a price that I think is reasonable, I won't buy.
That, unfortunately today, is business.