At my agency we have been playing around with the new block display and especially the width functionality is a very welcome addition. It really gives a great boost in usability to be able to control the layout of fields in the administrator.
On that note, one thing that would really give ACF a whole new place in our pipeline would be flexible fields as a sortable grid.
Imagine adding a flexible content field and defining a width of say 50% (from a dropdown). The width of the field group in the administrator would reflect this and only have a width of 50%.
Then being able to drag these fields around in a grid to sort (like you can now but only vertically).
This would turn flexible fields into a full blown page builder.