We have already Custom Functions and there will be Custom/External Script Steps. The next step would be Custom Layout Objects.
Imagine a tool (plugin?) that can create an object that you can use and reuse all over again in your solution.
Sliders, Min-Max-Sliders, ProgressBars, Dials, Meters, Gauges, Slide Switches, TriState Switches, Magnifier, Date and Time Picker, …
This object could be connected to a field value, using the current field value to modify the object accordingly. Interact with the object to change the field value, for example moving the slider knob will change the field value.