In case it is not already obvious, the Space Bar is already divided into 3 areas (left, centre, right). On the standard keytops these are labelled as CMD, 123 (Green Layer), ALT but they are not restricted to that use.
As an example In the Scandinavian layouts, the left side is used to access additional 'Green layers', whereas in the standard QUWERTY layout it is typically used as an additional way of getting CMD/CTRL (depending on target OS). The right-side is also used in the Emoji layout as the way of getting at the Emoji layer. I have no idea if the built-in sensors would allow for a finer level of graduation.
One of the limitation of getting additional functionality exposed to the end-user is going to be the TextBlade app providing a way of getting at that capability without making it dauntingly complex for the user who just wants a standard layout with no bells and whistles. So far I think that Waytools have done a good job in the app of keeping it accessible to most users. I certainly see this as one area that is going to continue to evolve after General Release of the hardware has happened. Hopefully evolving the iOS app is not going to hold up the development of the app for other platforms.