Atlas project lead here.

Atlas is an auto-regressive diffusion model, so context length limitations apply similar to LLMs and video models.

Where Atlas has an edge is that its context comprised of an arbitrary sequence of images with camera poses, which lends itself to managing the context in creative ways (we called this "context juggling" in our RTFM blog, https://www.worldlabs.ai/blog/rtfm). So yes through clever context management you could potentially build an entire 3D model of the world.