Not happening. Apple should and will focus its Safari development efforts on improving the browser, rather than porting it. I think they're content to leave the better browsing on Windows to Firefox.
I totally agree. There are plenty of browser options on Windows already (and Firefox is a pretty good option), so why would Apple waste their effort on porting Safari over. The only motivation Apple has to port any of their software over to Windows is to drive more hardware sales, like iTunes to drive iPod sales. Since the iPod and iPhone also sync with iPhoto, I could see Apple porting iPhoto over to Windows before they would bother with Safari.