Cliff living would not have made them bigger. They sold 15+ million copies of the Black album in the US and around 30 million worldwide. For a heavy metal band, which they were at the time, that is the ceiling. So no, Metallica is not a good example of a band that went to pot after their bass player left.
Here's a thought -- Jane's Addiction is actually a very good example of a band that nosedived after its bass player left.