Doubt it. People seem to be into Sigma as they are today for the cheesy vocals mixed with the uplifting music. Which they do well for their specific crowd. But give these same people tunes like 'The Jungle' or 'El Presidente' and they'll most likely defy the same artists for it. Point being, I don't think they like the genre, they just like the specific music Sigma are putting out right now.
Also, being 'the next big thing' is a pretty tough thing to answer in this day and age. Every few weeks there's a new 'next big thing'. DnB related, we recently had Netsky as 'radio flagship' and it didn't really make DnB mainstream.
Personally, I think DnB, as a lot of the people on this forum see (actually hear) it, will never be 'a big thing'. It's a niche genre for a specific crowd. A pretty tough to please crowd. But people are really passionate about it. As not-underground as it is these days, I still like to regard it as 'underground music', which makes it special to me.