Whether you are for or against adding technology to the game, video replays are coming to live action MLS games eventually. However, the recent history has shown us that soccer is careful and thoughtful about these changes.
When goal line technology was discussed people were split over it’s usefulness and impact. While there may still be someone out there who doesn’t support it, the addition has been positive for the game, with almost no disruption.
During the preseason the MLS ran the system for a select number of matches. The most notable one being the (correct) red card to David Villa after reviewing the replays.