Dear Dak! As far as I know, the battlefield will be larger during a siege (I don't know exactly how much larger). I hope this information is confirmed... :o
I didn't quite understand what you meant by your post.
Firstly, what is there to hope for when it's already a done deal?
And secondly, this fact won't bring anything positive.
However, my friend is already thoroughly testing the beta and says that it won't be difficult to adjust the unit stats for a larger battlefield and set the maximum field size (if desired, of course).
I don't know about the simplicity, but when switching from a small field to a large one, you only need to proportionally change the movement range of each unit and possibly the creature growth rate. This is an elementary task for modders.
I myself, after playing the beta, realized that the size of 8*10 is absolutely not suitable for me. It is only comfortable to play on it if the army consists of single-cell units and there are only 4 of them. IMHO, of course.