The reason bands become successful will usually be a combination of their talent and their likability. Losing a member can be a huge blow to a band whose fame (and usually fortune) are based on the group as a whole. Many groups have simply split up or suffered failing careers after losing a member but other have gone on to have the same, if not more success. Take a look at these bands who have successfully survived the loss of a band member.
This Australian band would have been forgiven if they had packed up their instruments when their lead singer died. Michael Hutchence had been the lead singer for 20 years when he was found hanged. Instead of giving up, the band continued to play with different lead singers for a few years, much like Queen. However, they then went on a reality TV show to find a new lead singer and JD Fortune joined the band. They remained together for another 6 years before calling it a day.