Little does he know that My Chemical Romance didn't release their first album until 2002. Although it was more likely that he found out about them from their second album which was released in 2004. But it's even more likely that he found out about them from their third album (which was their biggest), which was released in 2006. So that could be considered new. Also their last album was released around 2010, so I'll count that as still new.
Blink 182 didn't get very popular until the late 90s early 00s and are still going pretty strong. They're a bit more iffy, but I'd still classify them as new.
I'll give them Foo Fighters as they aren't too old, but they aren't too new either.
Green Day's first big hit was Dookie (1994). That would've been released before his birth, but they got really big again with American Idiot (2005) and sort of with 21st Century Breakdown (2009). So I'd still label them as new or at least pretty new.
Eminem was very popular in the late 90s and early 00s, but even more so when he started writing far more serious music in the mid 00s to the early 10s.
Ignoring all of that, Bieber only appeals to a specific demographic which is quickly loosing interest in him (that being preteen girls). That's a demographic that I can tell you from personal experience, doesn't fit with that of Lil Wayne's. And the funny thing is, Lil Wayne's career as a musician goes back to the late 90s, early 00s.
And want some good new bands?
Muse, Panic At The Disco, Foster The People, and many others! People like this act like music is dead. It's not. Music evolves and takes key elements from past generations of music and builds on them. Dream Theater, a prog rock band, takes inspiration from Rush, who takes inspiration from Genesis, who takes inspiration from classical music. Many modern day pop stars draw huge inspiration from The Beatles. Whether you want to believe it or not, they set the mold for many modern day boy bands, and could even be considered one of the first. Music changes. You may not like it, but it does. It molds its structure to appeal to the pop culture and social norms of the time it was released.
Sorry, just had to get that out.