While yours is a novel idea
, we would still need someone/something to keep players from wandering out on the field
. Another thought is to have the restricted area that needs to be clear during a play wired with players, coaches and the like wearing 'dog collers' that would zap anyone in said area during the play.
A sensor could be added to the ball that would activate the zapper once the ball is snapped. 
YOUR AND MY IDEAS ARE PROBABLY AT LEAST A FEW YEARS AWAY 
Back in the 70’s, working intramural softball at college, we worked on fields that had a backstop, but no other form of boundary marking. No fences. No bleachers. Nothing. Regular season wasn’t much of a problem. The few spectators that attended were easy to control. But, come playoff time, the frats would require all of their members to attend, with girlfriends, roommates, homeless vagrants - anybody they could find. Those unruly mobs were impossible to keep behind either an imaginary line, or a chalk line, on the ground extending from the corner posts of the backstop outward some 150’ or so. The unruly mobs would eventually migrate out to dang near the foul lines.
Then, one day, I noticed that we had several “tug of war” ropes in the equipment shed, and thought they might be easier to place along the boundary than marking with chalk (a task that was left to the highly paid student umpiring staff). So, we simply laid them from the corner posts of the backstop, outward, along the imaginary field boundary line. I suppose because these ropes were some 2” in diameter, the 3-dimensionality of the ropes seemed to emit a ‘force field’ of some kind, and they, magically, restrained the unruly mob quite nicely. It was quite easy for both umpires and mobsters to know that someone was over the boundary, and quite easy for the mobsters to know, and keep, their places behind the rope.
So, maybe require a similar soft, but fixed, three-dimensional boundary marker along the players’ lines (with the coaches in the pressbox). 😳. (We can dream, can’t we?)