I think 9W TDP might be enough for passive cooling. I don't get the 15W ones though. At 15W, they should compare their performance to the current Core i5 and Core i7 U CPUs, not the Atom.
CPU wise yes I can see it getting destroyed, GPU wise it would probably do the same to the equivalent I series Graphics. In short, things kind of stay as they are. Either way some interesting products are coming, and thats something to look forward to.