I doubt that is true. The FX will probably age fairly well as software tends to become more multithreaded. And since we're talking gaming, with AMD's console wins there is a very good chance that we'll see more multithreaded games in the future, not less.
I am not saying the FX is a better choice, chances are it isn't. But I don't think it is a worse choice, at least not for the reasons you say. How much power difference are we talking about on an FX8350 vs. a 2500k or 3570k in gaming? Do you think a game that uses one - four threads (as many, many games do) is going to be closer to the max TDP on an eight core FX chip that has half or more of its cores basically unused or Intel quad?
Again, I'm not saying AMD will be better, but I think the power use difference in gaming isn't nearly what some of you make it out to be... especially when we figure the whole system draw with two GTX580's or 7970's. In the grand scheme of things, especially with multicard, I doubt there is a very large difference.
The way I see it, Intel makes more well rounded CPU's. Intel blows AMD away in single threaded performance. Intel generally are better with power use. But as this article shows, and as someone who is still quite happily gaming on a Thuban CPU, I think most people would have a hard time telling the difference between an FX and i5 in *most* games at the settings you actually play at in real life.