There will always be new minds and new ideas to bring to the stage. With the advancements in science and technology, there will always be new material to discuss. I think we may start seeing a lot more from brain scientists. Particularly in the field of cognitive and developmental neuroscience.
I don't see how they would ever run out of ideas worth spreading. The evolution of ideas is just that, new ideas will always be thought up. The future will always have open minds and so will TED. You can't say that we will ever stop producing ideas, that would be awful.
No, TED will not eventually run out of content to produce, because people are still living. Just as a new day brings new stories for a newspaper to write about, TED will continue to have new content as long as the world keeps on turning. They have a creative team and will continue to do well.
I do not think that TED will eventually run out of content to talk about. There are a lot of topics and subjects that a program like TED can talk about. And a lot of people will always have differing opinions on subject matters. I also think that people will always have new ideas.
In this day and age, content is something that is easily produced daily if needed no matter what the situation. Just when you think there can possibly be nothing else created you are left surprised when the newest content comes out. I no longer believe that anyone or anything can run out of content unless they are not seriously trying.