No, I'm sorry; I wasn't very clear. If McCain were elected president and something happened to him, God forbid, which prevented him from continuing in office, his VP Palin would become the president. And Pelosi, the moron, would remain right where she is. She doesn't elevate to the executive branch unless something were to happen to both McCain and Palin (God forbid, again).
I'm not clear on whether a President Palin would have a VP and, if so, how that VP would be chosen. Someone else on here will know, however. My civics classes were long, long ago, and the only reason I knew that the truly moronic Pelosi would become president if both President and VP were unable to continue is that I looked it up when she became Speaker and was so horrified to find this out, I've not forgotten it.
Review Ford. The only unelected President.
In this circumstance, Palin would nominate a potential VP who would have to be confirmed by the Senate. Until then, the position would be vacant and the Speaker of the House would be next in succession.