Samoan. Let's not get into technicalities here. I think Jim Ross even said himself that he thinks Big E can become the first Black WWE champion, and then had a little back-and-forth with a fan who was like "ROCK!?!?". Let's face it, WWE don't consider him to be Black, lol.
If WWE were racist, they wouldn't put a title on a Samoan either lol. Funny how a lot of people have the weird perception that racism means hating on the black man as opposed to what it really means, which is treating any one race as inferior to any other. And when you look back at just black men in the WWF, how many of them do you think really had what it took to be THE top guy? Ahmed Johnson had the look but not the charisma. Bobby Lashley's voice didn't match up to his intimidating look (his body, not his head) at all. Booker T. was entertaining but seemed like more of a mid-range guy and not someone you'd rely on as the top hand. Shelton Benjamin was a charisma vacuum. Rodney Mack? Nothing special. MVP? I don't see "the face of WWE" in him either.
As for the topic, I don't really agree with Daniel Bryan or Dolph Ziggler being the guys who could take Cena's spot. Bryan is a workhorse, he is over, he can sell merchandise, but it still remains to be seen if he can actually be relied on to sell tickets or sell PPVs as the main event attraction, the #1 guy that people pay to see above all others. I don't think he'll ever quite reach that level but he can still be an essential part of the main event scene, and similar to Jericho, drop down here and there to win the Intercontinental or United States Championship to help raise it's prestige now and again. As for Ziggler, I don't see anything that screams Main Eventer. He's a workhorse too, but he doesn't have much of a character that draws me in and seems more fit as a heel who can win the titles now and then just to put others over when dropping them to him. How well he does as a baby face is still to be seen. I think Big E Langston would be a second tier kind of star as well - maybe a frequent main eventer but usually as a challenger, maybe a title reign or two, but I don't think WWE will put all their chips on him to carry the company.
I personally doubt the next face is part of the active roster yet... Unless someone does an unexpected complete 180 and turns into something completely different (like a Rocky Maivia/The Rock transformation, even though Maivia still had charisma in those early days) and surprises everyone. I personally would be fine with not having another top face for at least 2-3 years after Cena retires or is relinquished from the top spot. I'd rather just have a group of guys who are top tier main eventers but none of them really stand out as the definite top face (Foley, Undertaker, Edge, Orton, CM Punk, HHH, etc.) It makes things less predictable since you know there's not just one specific guy who's gonna hold the world title for the majority of the time and get the Wrestlemania main event and victory virtually every year.