The World Series will require WWE Friday Night Smackdown to move to FS1 on Friday October, 28. Game 1 of the World Series is scheduled for that Friday night.
However, if Game 6 is necessary, it will be played on Friday November 4th, which would then see the show airing that night on FS1 as well.
FOX will be airing the PAC 12 College Football Conference Championship Game on Friday December 2, which will require Smackdown to air on FS1 that night.
Source: PWInsider