“Hollywood is part of the answer, but at 15-25 3D films a year and with long lead times it cannot keep pace with the demand,” said producer, director and 3D advocate James Cameron.
It may not make sense by business model, but I see two reasons to continue it for events such as sports events.
Different angles are best for each. For 3d lower angles that show greater depth make for the better shots. For 2d higher angles that can show the whole field and relative positions work better
Currently broadcast can only use side by side or top bottom for 3d. And seperate channels are therefore needed. This means that different sponsers are usually needed for 3d broadcasts.