Now That Rap Is Mainstream . . .

After a year in which a rapper from St. Louis (Nelly) took the hip-hop nation by storm and a white rhymer from Detroit (Eminem) became the biggest music star rap has ever produced, hip-hop is facing what will be a critical year in its development. Now that it has become commonplace in all forms of media, what is it going to do with that presence?

The big questions:

Will it continue to develop more subgenres and become more regionalized than it already is?

Will arena rap tours be increasingly successful?

Will forward-thinking groups such as Slum Village and Talib Kweli & Hi-Tek continue to be ignored by the hip-hop nation?

Expect all these trends to continue, especially with underground albums being released at an unprecedented rate and mainstream hip-hop fans becoming more and more loyal to single records rather than to artists.

Here are the intriguing things to keep an eye on in 2001.

* The much-delayed comeback album from Run-DMC, “Crown Royal,” may finally arrive in stores in February, a year and a half later than planned. The collection from the seminal Queens trio was shelved after Kid Rock and Limp Bizkit’s Fred Durst were denied permission by their record companies to appear on Run-DMC singles, according to published reports. The group also had to deal with member Darryl McDaniels’ interest in making a kind of folk-inspired hip-hop album rather than working in the group’s signature hard-core style.

The collaboration-heavy album features top-tier guests from both the rap and rock worlds, including Kid Rock, Limp Bizkit’s Fred Durst, Stephan Jenkins of Third Eye Blind, and Nas. It speaks volumes that the group and its label, Arista Records, feel that a new Run-DMC album needs guest stars to succeed.

* Detroit-based D-12 will also benefit from collaborators on its debut album, which is due in March--mainly Eminem, its mentor. D-12, which appeared on Eminem’s controversial blockbuster “The Marshall Mathers LP,” will be the first act to release an album on Eminem’s own label, Shady Records. Although Eminem will bring clout and chaos to the album, it would likely be a nonevent without him. D-12’s collaborations on Eminem’s album, “Amityville” and “Under the Influence,” were widely regarded as the collection’s low point.

* Bucking the collaboration tide, Mos Def is simultaneously recording two albums whose success will be determined primarily by Def himself. The New York rapper is working on his second rap album, “Hated by Them, Loved by Them, Respected by All,” as well as his first album with Jack Johnson, the rock band he is fronting.

It includes guitarist Dr. Know of Bad Brains; keyboardist Bernie Worrell of Parliament/Funkadelic, Talking Heads, et al; and drummer Will Calhoun and bassist Doug Wimbish, both of Living Colour. Jack Johnson cut its teeth as unannounced headliner on the Lyricist Lounge tour in 1999. Mos Def previewed the rap-rock sound on his debut album, 1999’s well-received “Black on Both Sides,” but rappers who dip into rock have seldom found critical acclaim and commercial success at the same time.

With his straight-up rap album, Mos Def is likely to remain at the forefront of the uplifting, positive rap movement. With A Tribe Called Quest disbanded and De La Soul abandoning social commentary on its last album, there is a void in honest-but-reflective hip-hop that Def can help fill.

While Mos Def will woo listeners with his politically charged work, there are plenty of rap poseurs hoping to cash in on their celebrity status.

Take Allen Iverson, for example. The Philadelphia 76ers basketball star is preparing his debut album, “Jewelz,” which is scheduled for a June 13 release on Universal. Iverson brought his flair for controversy from the basketball court to his new project late last year when tracks from his album made their way to the NBA’s corporate offices, where the suits didn’t approve of Iverson’s language and themes, which included talk of guns and disparaging remarks about gays and women.

Many of the biggest stars of 2000 will be releasing offshoot projects on vanity labels in the first half of the year. Eminem has D-12, OutKast has Slimm Calhoun, Nelly has the St. Lunatics, and Jay-Z has DJ Clue and others. Another of last year’s big successes, Lil’ Bow Wow, probably won’t have his own label any time soon, but that’s only because he’s 13.

GOOD RIDDANCE: Two artists glad to say goodbye to 2000 are certainly Lil’ Kim and Master P.

After many delays and more publicity than a Robert Downey Jr. arrest, Lil’ Kim’s second collection, “The Notorious K.I.M.,” tanked critically and was a commercial letdown, reaching sales of just 1 million copies by the end of the year. Without her mentor, the late Notorious B.I.G., guiding her direction and helping her with her lyrics, Kim’s rapping career is on life support.

Master P’s fall from grace is also noteworthy. Unlike rival rapper-mogul Puff Daddy, whose Bad Boy label had hits in 2000 with Black Rob, Carl Thomas and Shyne, P and his No Limit label scored with only a platinum album from the 504 Boyz. With the departure of fan-favorite Mystikal and the production team Beats by the Pound, Master P and No Limit found that there is a limit after all.