It seems like the most logical thing on the planet to me, and it should be universal in every major sport. In every arena create a small room with the best camera feeds, a computer with access to the feeds and a really big monitor. Everything that should be reviewed is. Out on the bases, completed catches, out of bounds, shot clock violations, etc. There aren't enough of these kinds of close plays in a game that a game should be drastically lengthened, and officials get the calls right most of the time. But when there's a question, have that review booth on top of it to make an immediate call down. No challenge flags or timeouts or umpires running to a monitor. Hell, in MLB and the NFL I bet the games get shorter. Managers won't run onto the field, NFL refs won't huddle next to a monitor. Again, for years this has seemed like the dead-simple option and I can't believe it isn't universal by now.