Dude, where's our singer?

Fascinating article from the NY Times about lead singers being replaced in bands: This Band Was Your Band, This Band Is My Band. I wonder about some other examples from past music history. Once the rest of Pink Floyd kicked out their former leader, they reached untold commercial heights though some (including David Bowie) insist that the band was never worthwhile after that. A similar case could be made for AC/DC- it might have been unimaginable to replace the singer at the time but they did and reaped gold for it. Then you have the vocal groups from the 50's would get replaced regularly by their management or label but still do amazing work thanks to a great stock of producers and songwriters (i.e. the Drifters). Other interesting studies are the Move and the Byrds- in both cases, the singer left after a few records but the band was able to carry on (not as commercially successful though) because the band's force of personality came elsewhere, from the main songwriter (Roy Wood, Roger McGuinn). When you have leader as both the singer and songwriter, you're asking for trouble trying to replace him- just ask Mott (the Hoople). This doesn't work well for rap crews it seems also- were Brand Nubian, NWA, Goodie Mob ever the same once their honchos split? On the other hand, you gotta respect groups who recognize the unreplaceable quality of their leader so that they move on but also change their name- Joy Division, Sublime come to mind. All in all though, it seems that singer-replacement is part of a grand old tradition.