A couple of thoughts on migration to Australia (Greater & Lesser)
I still say, on the whole, that North Island and much of the Australian coast is more attractive climatically than most of the land in the DSA. The DSA also has a high birth rate, with plenty of native-borne settlers who can take claim of western lands easier. If you're moving from Britain and looking to start a farmstead, Australia is by far a better bet.
For free settlers just looking for a cheap ticket elsewhere, there is no doubt they'll go to the DSA initially.
As to convicts, I don't think they'll play a particularly strong role in the British Australias. Sydney was founded as a penal colony in large part because Britain couldn't send convicts to North America anymore. Before the Revolutionary War, convicts were indentured servants, usually on plantations, so with the retention of most of the plantation colonies, there is no reason to assume Britain would stop doing this. At least until the DSA gets home rule - it's possible they'd then ask Britain to send them elsewhere because they were troublesome, but by then, Patagonia is open.
Instead, I think the developing Australian ruling and middle classes will look closer to home. There will be more "blackbirding" of natives of nearby islands, and more immigration of Indians, Chinese, and Malays. On North Island, the Maori will be ground down into being the laboring class for the British, one way or another.
But once the Gold Rush starts all bets are off. There will be a huge increase in British migration. However, I'm guessing half or more will come from the DSA, simply because it's far quicker for Southrons to get to Australia than Britons, and it will be far cheaper travel as well. Victoria* is liable to have a southern drawl to some extent.
Overall, I'd say you're looking at a majority-white *Victoria and *Tasmania, and a majority nonwhite *Queensland. New South Wales, South Australia, and North Island could go either way depending on how much of a later migration draw the British Australias become.
As to French Australia, it will be very white, outside of a dusting of South Indians and Blacks in the major cities. Nowhere is really suited for plantation agriculture, and native inhabitants are very thin on the ground. I actually think this will probably butterfly away French settlement in New Caledonia and Tahiti (assuming they own these) to some degree. It probably means there won't be more French migrating to the USA ITTL as I previously supposed as well, unless a French government institutes natalist policies unlike IOTL.