People who entered the NBA in the 80s are not the new NBA to me. If I was a decade or two older then, yeah, these people would be the "new NBA" to me.
I just chose an arbitrary time period when many of the 80s legends were retiring. But some of the 80s legends were still in the NBA in the early to mid1990s. They can be legends who just hadn't retired yet.
I just see a clear change in the excitement of the NBA that happened in the mid1990s and 2000s. So the newbies of the mid1990s and 2000s are the new NBA and I wouldn't consider these people to be legends.
Mutombo was good when he was drafted in 1991(?) and had a cool career. But beyond his notoriety I wouldn't call him a "legend."