I find it funny a man can be called a legend when he still has not grabbed the attention of all people, and he's still alive. Elton John is not a legend himself, and he calls Eminem a legend? Elton John may be beloved by English people, but let him leave that country, and make a name for himself elsewhere. When he does that, he'll become a legend.
Eminem has not been in the rap industry for ten years, and he's already called a legend? He will become a legend, but not today. Wait till he retires and has snatched enough awards.
Trust me, he's nowhere close to the love Pac and BIG get. When you get anywhere close to the love they get, you'll become a legend. DRE is a legend cuz he's been such a long time, and he has achieved a legendary career as a producer.
Legacy pretty much comes with the love you get. Eminem has no credibility amongst Hip Hop heads, and his "few" memorable hits won't place him amongst Life After Death, All Eyez On Me (eventhough this is not Pac's best album), Straight Outta Compton, and OGs like Run DMC.