Three issues: availability, accessibility, and acceptability. Is the tech available to call lines with 90% accuracy. Two, is the cost prohibitive? Three, how do they get deployed?
I would allow any player that has one to use it on his or her court for any USTA sanctioned match. I would not make it mandatory. How could you? Most country clubs would be able to afford a few devices.
Let's imagine that automated line calling tech comes down in price to where it's available for $50-$100. We're not there yet, but maybe in a few years.
It would then be something we could compare to use of singles sticks.
Is it necessary for rec play?
Singles sticks are not necessary - it's not going to make a significant impact on the outcome of a match.
Similarly, I don't think automated line calling is necessary - really I don't see that many obviously bad line calls.
So I don't see it getting to where it's mandated, just like singles sticks are not mandated.
Should it be allowed for use in rec play?
Singles sticks are allowed if they are provided by the facility and are approved/regulation sticks.
I think it should be similar for auto line calling; if permanently set up for the court (and so one assumes calibrated correctly), it should be used.
The grey area is where the singles sticks / auto line calling device is not provided by the facility but brought by one of the players.
In this case I think you should need agreement from all players to use the sticks / device.
Because there is some trust involved in buying into the quality / accuracy of the sticks / device.