You're right. The sons of dead members still are involved with gambling,loansharking and other things only that they know that can easly made money without a formal hierarchy and that risk less time in jail because the feds can use the Rico so easy if there are a mob family.
I rrad an article of a son of drad members that was caught for gambling and eas making dozen milions and get few years where he could risk more if he would be a soldier.
That why the small families wasnt rebuilted:they can make money without LCN family.