I personally believe that religion will decline over the next few decades and will then make a comeback in a big way. When ideas go into decline they are usually rediscovered, recycled and repackaged and then hailed as "new".
If human development were to take a left turn into chaos, religion would immediately resurface as a tool for control, rule of law and general order.
If human development continues in its technological strides forward, religion will just be repackaged as a fundamental life philosophy, which is essentially what religion is anyway.
In the meantime the debate between religion and atheism is pretty neat and I have my popcorn and soda ready for the next exciting chapter. The conclusion to this debate on the fundamental meaning of life (which usually is at the core of these contests) is actually forgone though: No matter what, no one gets out of this alive.