This phone-calls-with-celebrities model has been tried many times before but it simply isn't viable in the longterm for various reasons. Clearly you can get people to do it occasionally and even enjoy it, so it's great for things like what exec is doing, but it's not something that many people would do on a regular basis.
That said there are definitely still unexplored variations on this idea that have at least a decent probability of success, so I think it's worth it for those seeking ideas to take a closer look here.