A better question is when it is not matter what content is formatted for, only that we can get to it. As a website designer, I get into the mindset at times that content is dependent on the device, that is totally wrong and always degrades the quality of something because someone who should not be is excluded. I believe that the next revolution in content should not be that which is based on whether it goes mobile or not, but rather whether it can go anywhere or not. That is more important in terms of technology having the great benefit to the greatest amount of people IMO.
[I tend to be a bit passionate about accessiblity so please excuse if I deflated this convo already]