The new terrain algorithm is amazing.
I know that this this is a very different technology so that it could not be implemented that easily in SE but I think you could be interested by this video about near-instantaneous terrain generation + erosion from deep learning algorithms trained on actual terrain data.
Hey this is really cool. So to briefly sum up what's going on here, there is no actual simulation of geological processes or erosion, rather the neural network has been trained to produce heightmaps that
look like actual terrain. One of the key features of neural networks is that they're highly parallelisable - allowing the computation to be offloaded to the GPU.
This means there is no fundamental computational limitation to having such terrain generation in SE. Getting it to generate convincing non-earth terrain, however, would be a bit trickier and would need someone dedicated to do it.