Would be a field that uses clear/transparent turf. and all colors on the field are defined by lights under it. The white in the 10/20/30... could be done dynamically, the end zones could be designed dynamically and relit, heck, you could switch from a green field to Boise State's blue.
This could be used to make the same field a football field, soccer field, lacrosse, field hockey... all without the the clutter of all the lines on one field.
This might be tricky with turf technology currently, but I feel like a first technology to do this might be a basketball court (lights for basketball, volleyball, etc)...
It probably isn't feasible, but would be interesting.