Is it at all possible to have a populous, formerly colonial nation in the Indian Ocean?

Question

The temperate latitudes of the Indian Ocean and adjacent regions are essentially empty- only the extreme Southwest of Australia and extreme South of Africa dip into the temperate belt.

What if there actually was significant land there in the 40s South?

There are essentially two options:

I- The "Realistic" Option: The Kerguelen LIP (perhaps including the Broken Ridge and Ile de Amsterdam still affixed to the rest of the plateau) is still very volcanically active for some reason, and an area over twice the size of Britain, and perhaps larger than France is above the water from latitudes 43 S to 53 S (parts of the Kerguelen Plateau were subaerial IRL as recently as 20 million years ago).

Depicted: the Kerguelen LIP.

II- Complete ASB Option: There is a large continent, possibly the size of India or a bit larger in the same general area, stretching from 40 S down into the 50s S.

Climate

The main difference between these options is the climate that they imply (lets assume that there will be no impacts on the rest of the world, or else it is a moot point to discuss whether or not European colonizers could have reached these places).

In the first, "realistic" case, geologically speaking, the land is like Iceland, comprised mostly of basalt and crowned with broad volcanoes that reach as high as 2.75 km. The climate would likely be cool- but warmer than IRL Kerguelen. Still, in the north it would be marine with cool summers and near but likely above freezing winters (this could easily support forests such as those on the South Island and in Valdivia). Further south, of course, temperatures would slowly become cooler until the Southern edge would have a climate like the actual Heard and McDonald islands- tundra/ice.

In the second, its geology is indeterminate as it is not based on the Earth's actual history. Its climate though would be more seasonal and therefore warmer in the summer, though with potential for harsh, continental winters especially in the interior and south. At the far southern edges, the climate would still likely transition to tundra as the land is deeper into Antarctic waters.

In both cases, the climate will likely have ample, frequent rain and be exceptionally cloudy.

Utility

Many may be inclined to dismiss settlement on either of these hypothetical landmasses entirely, but that is overly hasty. As the land is larger now, only the coast is scoured by the constant westerly circumpolar winds. Owing to their size, both would be able to support forests in at least a portion of their land (geological expeditions to IRL Kerguelen have revealed that when the plateau was exposed, it was home to forests, as evidenced by fossilized wood). In addition, the fishing and whaling on the west coast of either land mass would likely be some of the best in the world, and again, owing to larger size, increased continentality, and a lower latitude at up to 40/43 S, summer temperatures would generally be warmer than at comparable latitudes in IRL Kerguelen). Also, though this more minor, Kerguelen is home to a species of "cabbage" which is a useful source of Vitamin C.

Settlement and Main Issue

So, with the land and climate in mind, is it at all possible that a European colony founded in one of these scenarios could become more populous and therefore, more economically important and powerful than Australia did in our own world? Is it possible that a subaerial Kerguelen LIP could be like a Southern Britian, or a large southern continent perhaps even a 2nd USA or Brazil?

As for who would settle there it is uncertain, but the landmass could be hypothetically discovered as early as the 1520s and would almost certainly have been found and realized to be a large landmass by the 1640s. The Basque or Portuguese, later Dutch settlers, or the British and Irish are all possibilities.

A question sort of implied by this one is why did Australia receive fewer immigrants than the United States? In the latter decades of the 19th Century alone, the US received more immigrants than the entire present day population of Australia.

If this is due to proximity to Europe, then I think an Indian Ocean great power or even regional great power would be out of the question. But if it is due to the lack of Arable land in Australia, maybe there is a chance. Or perhaps there is another factor, social or political that motivated the disparity between the two. This would have a large impact on whether or not these landmasses would have a future beyond seasonal whaling bases or sparsely settled sheep stations.

Thanks for your input

Answer 1

Either option is certainly imaginable.

I'd argue, as an armchair geologician, that option 1's Kerguelenlandia would not be appreciably warmer there than it is here. And the reason is that pesky Circumpolar Current. Keeps everything down that way, even lands that do jut into the "temperate" zone, and there aren't very many, far too chilly for comfort. I suspect that Kerguelenlandia will be cool in the north, probably much cooler than southern Kiwistan, and southern Kerguelenlandia will be Icelandic or worse.

Your second option I think might be better. If the ASBs just did a proper Magellanica, rather than a tiny Antarctica, we could dispense with the Circumpolar Current and Kerguellenlandia (formerly Los Romeros) would be more temperate.

Either way, as for who would get it, I'd imagine that the Dutch and Portuguese might try, but Britain I'm sure would give its left nut for a large resource rich land that didn't have a bajillion poisonous species of everything (Australia) or Natives (Australia & Kiwistan). Forests are good for ship building. I'd imagine land in that zone would be as good for sheep as the other British territories. It's a little off the beaten path, but if you posit a sufficiently resource wealthy country, then it would make an ideal southern arc between South Africa and Australia.

If it ends up connected to Antarctica proper, then things become interesting in the 20th century when other countries want to start exploring!

Due to its distance from Asia, things would also become interesting in the 20th century when WWII begins to loom large. Keep in mind that Imperial Japan's maximum zone of control came very close to the Australian coast, and they did in fact attack many cities and places along the northern coastal regions. Kerguelenlandia would surely become an extremely important location during WWII.

An interesting knock-on consideration: it is possible that if Kerguelenlandia were settled & colonised during the 19th century, and became even moderately industrialised, it could very well have diminished Hong Kong's place as a manufacturing powerhouse: why would the Empire bother with investing in a couple tiny islands when they have bloody rich, bloody big continent that is not filled with squillions of poisonous leaping rats and venomous spiders out the yingyang?