Wel,it's not really that they're "dropping like flies".
Some left because it was their time,others because they did way too many drugs and drinking in their hey-days.
In Les Paul's and Walter Cronkite's cases it was just their time.
In the sadder case of MJ,his life was taken from him but if what is said about his demands is true,then he had a hand in it as well.
Every few years it's like this unfortunately. 1998,2003 last year (Paul Newman) and now.