The fact that children's music sensation, The Wiggles, are replacing three members would probably be a lot more traumatic to me if I knew anything about them.
I'm sure, though, there are millions of toddlers who will opine that The Wiggles will never be the same.
It makes one reflect on the bands that have replaced members and kept right on going. The Rolling Stones have done it several times, for instance. And there are those who still contend that they were never better than they were with Brian Jones. Van Halen did it, and their Sammy Hagar-fronted record was the band's first album to hit #1 in sales.
Can you think of any bands that have replaced members and not missed a beat? Maybe they've even gotten bigger/better? How about the opposite: replace member, go downhill?