A 1024 brick square piece of terrain consists of 1,048,576 bricks. That is assuming the terrain only has 1 brick vertically per 1 grid slot. It is way over the current limit of 256,000 bricks. A more reasonable size of for a repeating terrain chunk would be 357 bricks which would equal to 128,000 bricks. This is still assuming only one vertical brick.
It is still a theoretical value so lets assume 16 bricks vertically per one grid slot with the total of 128,000 bricks for the entire terrain chunk. It equates 89 which would be close to a single 64 base and one 16 base. These are still rather theoretical values as I am assuming terrain consisting 16 layers of 1x1 bricks but it is still a much better estimate than a 1024 by 1024 brick area.