Keep the lines and rules the same. Just replace linesmen with cameras or sensors that can blow the play dead immediately when an offside is committed. This is the perfect job for a machine. You'll never need a review or a challenge.
It's not that easy. You need however many sensors to be able to accurately detect every part of players that could potentially be across the line improperly, so probably on skates and in the puck. I know they should have sensors in the pucks now for the upcoming tracking, but regarding the skates, you still have account for whether it's on the ice as you cannot have the skate in the air above the line and be onside. What happens when the foot is contorted in some strange way unlike regular skating? Do you need a sensor for every dimension and yaw as well?
Cameras and a neural network to read the images could work, but then you run into issues of occluding the image from whomever in front of the camera so how many cameras do you need to account for all angles and possibilities because some angles cannot read height over the ice for example. You could probably combine networks processed by multiple cameras, but I don't know how fast that can all be done. You are trading off accuracy for speed in all likelihood.
Finally, there is going to be an error rate, and knowing fans, if it's ever wrong, oh boy. What's acceptable and are you still going to have the War Room watching over the whole process to account for false alarms and misses? What's the whole point then? Just keep it as a manual review. That doesn't even account for the suggestion to blow the play dead automatically. That needs to be a zero error thing.
I'm not saying it's impossible, but I don't think you can get it done in real-time at an acceptable performance anytime soon, especially considering how long it has taken them to get tracking set up, where we're hoping they debut it during the conference finals.