If the lanes were re-opened, traffic would immediately improve along the route. People would notice the lack of traffic, and start driving more, since now it's convenient. The number of cars driving would increase until traffic was so unbearable that people are encouraged to use other methods of getting around, changing when they make their trip, or just don't make the trip at all. If the bottleneck isn't in this section of road, it'll be somewhere else along the route, but somewhere is going to be completely choked in traffic. This plays out over and over again with every freeway widening project, I don't see why we'd expect this to be different.