Although the observed universe is considered homogeneous, there are small local inhomogeneities in it. These are galaxies with higher density, and voids with lower density. In the region of galaxies, space is more curved than in the region of voids, and on average throughout the observable universe it is almost flat.
Let's say that the entire universe is many orders of magnitude larger than the observable part. And let's say, sometime in the future, more accurate measurements will show that the space in the observed part is slightly curved.
Could this, among other models, correspond to the following scenario: the observable universe is a tiny portion of the cosmic region of high density that positively bends space. This region is analogous to our galaxies. There are many such regions. However, there are also regions (again, much larger than the observable universe) of low density in which space is either flat or negatively curved (analogous to voids). And on average, these "mega galaxies" and "mega voids" make the entire large Universe flat. Could this kind of large-scale structure exist?