Rappers that I think fell off are

Lil Kim(she never was on to begin with,but her sales are at an all-time low)
Snoop Dogg(used to be gangster,now just messed)
Jay-Z(bunch of hold over bullshit till Black album)
ODB(never really ill,but his new shit is just that,shit.Wu is better off without him)

just to name a few....