Unfortunately, most of the rail systems operating today face enormous costs for unfunded maintenance backlogs. In addition, most systems are experiencing declines in ridership. I know of no city where criticisms of rail systems go away once it is built. Fixed guide way transportation systems have limited scope, in that it serves a narrow corridor of customers. It is not a question of what would happen if nothing is done, the question is, "Is there a better way to relieve congestion?" The answer is, yes. Bus Rapid Transit was among the alternatives to rail. Busses go almost everywhere and can run with much tighter headways than trains,  thereby, moving more passengers at a much lower cost per passenger mile. Train systems are incredibly costly to build, operate and maintain. "That Vision Thing" is going to costs us far more than building this thing.