Baseball should be the easiest sport (besides Tennis) to eliminate the human element completely. Football, basektball, and hockey all have penalties, fouls, etc. which are often subjective. Baseball has almost none of that. The only exceptions are balks and check swings. Ball vs. Strike? The Foxtrax in the corner of my screen already answers that. Put it on the scoreboard. Safe vs. out? The only problem is lack of camera angles. They can add more if they start replay. There will never be a single call wrongly overturned--there will only be ones that literally will be a tie--and then you go with the call on the field like the NFL does. Fair vs. Foul is the same way, and even that can probably be automated like Tennis. I even think check swings could be automated, you just need a little laser/sensor in front of home plate or one of those tiny cameras looking straight up. They do not need to fire the umpires, they will be responsible for keeping the game moving and dusting off home plate and the little sensor.