I do not know how I feel about this. These two shows hold very special, yet very seperate places in my heart. If they were to cross over like how you are suggesting, I am afraid that it would probably suck, not to mention that it would probably never happen. Although 'Buffy' was (once) a very hip and popular show, and 'The Simpsons' tends to spoof just about everything, I just cannot see them devoting an entire episode to a spoof. I can maybe see a brief cameo appearance, or a single-scene spoof, but I think it is more likely that she will just play as a guest character, like she did on 'King of the Hill'. But even that might not happen. These rumors of guest appearances are very common, and often do not come true, like when Britney Spears was supposed to be on 'Buffy' as a big bad, or when Jim Carey was supposed to be on 'Friends'. I guess it is possible, but I wouldn't start celebrating yet.