I would go in the opposite direction and have more umpire's on the field. Kind of like how the playoffs are ran where you have two OF umpires. I would also expand it even further than that and add one or two umpires for disputed calls. The umpires would then be able to see it in real time and then have the replay to judge safe or out and fair or foul. You would still need a home plate umpire at all times as you need one to be able to see many of the nuances of the game which includes catcher interference, foul tips, fair and foul balls, a foul ball hit off the foot, bunt attempts, check swings, hit batters by a pitch, relaying the count and outs to the batter catcher and pitcher and safe or out calls at home plate. There will always be a need for a home plate umpire they just don't need to be calling the balls and strikes anymore. To be fair the home plate umpires job is already one of the more complicated things in baseball as they need to keep track of the lineups and substitutions, calling balls and strikes, calling foul tips, calling foul balls, determining if a batter was hit by a pitch, catcher interference, safe and out calls, balk calls and batters interference.