To me it seems impossible for a finite being to observe an infinity.Would it be to much of a stretch to say that it would be impossible to ever determine the size and shape of our universe because we are naturally a part of the universe with a limited view.
If somehow we could detach ourselves from the universe (i.e an aerial view of the landscape reveals much more than being on the ground) then we would be able to determine the dimensions of the universe. Whilst we observe it as a whole
The observable universe is obviously finite, so it can expand to its heart's content without offending our logical sensibilities. It is also very close to being dead flat - according to WMAP and supernova studies. This suggests the universe is much larger than the part observationally accessible to us. In is, however, possible the universe could be both flat and finite.
This is pure speculation on your part and should be stated as an unsupportable opinion, not a fact.