Saying that people will stop caring about viral marketing is suggesting creativity is finite.
What has happened due to the YouTube revolution is that it is harder to be funny now. Notice it's just HARDER - not impossible. So while in the past year or two folks might have gotten around producing average stuff that became viral, the same level of creativity won't be viral in the future. I think that is the real point the article is trying to make.
I don't think he's asking how long until people stop caring about viral marketing, but how long until people stop caring in general, i.e. about humanity. I think the problem lies not in viral marketing itself, but in Nissan's implementation of viral marketing. I think that the methods of these different types of viral marketing are analogous to the goals of white hat and black hat hackers. A practice that may be generally good and clever can be thoroughly spoiled by those who take advantage of it for the wrong reasons.
What has happened due to the YouTube revolution is that it is harder to be funny now. Notice it's just HARDER - not impossible. So while in the past year or two folks might have gotten around producing average stuff that became viral, the same level of creativity won't be viral in the future. I think that is the real point the article is trying to make.