The reason there isn't a new one is because of the whole "hip hop is dead" movement. fukking nas

Listeners and the general public are too reluctant to give their attention to a popular rapper, instead opting for the lesser known underground choice who, most of the time, lacks the star power or the interest to become the next big thing. That in turn squeezes and sifts out the very few underground rappers who have a mere sliver of stardom and forces them to be propelled into the limelight. Take a look at Kendrick, J. Cole, Wale, Meek, etc. They're not stars by any means but they've been shoved down our throats as such. Drake and Nicki are definitely the two new megastars of today, but their current music is hardly considered hip-hop to be quite honest.
Now, to be a star, you have to have crossover appeal and entertain corporate fukkboys. the obsession with underground and backpacker lyrical rappers has crippled mainstream legitimacy and ultimately it discourages new artists to broaden their horizons and give in to industry demands every once in a while. Also, you can't be big if you don't have a mentor or a huge co-sign. Kanye had Jay, Drake has Wayne, Em Snoop and 50 had Dre, Wayne has Birdman, and so forth. Oh and they also have to have a larger than life character or a kind of messiah complex. And finally, the most important thing: hits. No hits = no starpower. And I'm talking Billboard Top 5, platinum 2 months in kind of hits, not those borderline hits everyone talks about.