WWCF: Sensors in Football or AI Calling Balls/Strikes in Baseball?

Which will come first?

Sensors in the NFL (determining touchdowns, etc.)

or

Artificial Intelligence Calling Balls & Strikes in the MLB

Basically, which of these two professional leagues will first adopt a replacement for human officiating judgement? The Hawk-Eye system has been finding wide adoption in many sports with tennis being the most substantial example to date.

For decades now we have had greater and greater use of replay review. NBA basketball is perhaps the most developed version of this even if it is imperfect. And despite the old-fashioned nostalgia and general complaints ("they still don't get it right!" . . . "it takes too long to be worth it" . . . et al. ad nauseam), I don't think the trend of trying to get it right with the help of technology is reversing.

You don't have to look far for examples of meaningful mistakes in both sports all of which are painful for fans and damaging to the brand. But vested interests (unions and fans who fear change, to name just two) hold back improvement*--slowing us down from where we are otherwise going. 

Here are the terms: 

• Football - in the least having sensors used to determine touchdowns when the officials on the field are in doubt. It would qualified if these are used to overrule upon challenge or if the officials can use them similar to how every score is reviewed by rule.
• Baseball - in the least the calling of balls and strikes by an autonomous system. To be clear this is not overruling the umpire but autonomously determining in the first place. 

Baseball would seem to have the clear lead in this evolution. However, football would be less disruptive since this would only be employed at critical plays like scoring (the criterion for this WWCF) as well as potentially first downs and out of bounds. 

My prediction: The MLB has more to gain as that sport is much more at risk of losing fan share. It also has obviously been making more moves in this direction. Therefore, they will opt to make a leap out of a greater sense of urgency thus being the first mover.

*One could argue that there is some art involved in catchers framing pitches as well as potentially some game improvement by umps having degrees of freedom in the strike zone. However, the spirit of the game is probably not in how sly a player can deceive, and it takes ~25 umpire "improvements" to negate one obviously blown at bat. Likewise in football I fail to see anything desirable about referee mistake.