With Vh1/MTV switching/focusing more on Celebreality coverage and reality shows about young bytches getting knocked up and Mafia wives and all that bullshyt, the spotlight that was focused on alot of mainstream rock acts has gotten dimmer as the years progress, new music/genre and the resurgence of Rap with it's more 'controversial' image as of late with the trap/drill wave, ain't much coverage being given to current mainstream acts as well as up and commers compared to what they'd get easily from 99 up until like say, 5 years ago. And by coverage, I mean universal coverage, where the videos are played in rotation all the time, media writeups are front page as opposed to tucked away in the middle section of a Rolling Stones or a Billboard 100 and shyt like that.
But then again I don't live in America where alot of the rock I'm talking about originates and is cultivated so I'm not too privy to seeing new shyt and to be honest with you, I stay away from mainstream rock acts like Maroon 5, The Killers and all that other poppy shyt that ain't for me short of shyt such as Chavelle, some parts of Muse and The Strokes, so I could just be out the loop, but you can definitely see the shift current day rap has over current day rock in terms of promotion and mainstream presence, especially due the rise of the "Mixtape" which gives rap artists and rap in and of itself a bigger boost in generating content since a rap artist can release 2,3 mixtapes which are essentially free albums worth of music at little to no cost, generate a HUGE buzz, jump on a tour and be in the spotlight compared to a rock act who'd simply tour, get a write up for being a popular band to keep in the spotlight, announce a new album "
We're working on a dark heavier sound with RickRubin on the couch. I think this is going to be hour most heaviest album yet!" (lol, fukk a fullstop.)
So with all that shyt being said, you aren't seeing a bunch of new acts replacing the older ones from back in that era, no one replacing Coldplay, No one replacing Tool, no one replacing Maroon 5 or Franz Ferdinand or Korn or Papa Roach or System of a Down mainly 'cause they ain't getting that media push they once had that had you hearing shyt you didn't even know you wanted (Trapt - Headstrong (

), Keane - Somewhere you belong (

), Adema - The way you like it.

) just out like that shyt, nah you got to SEARCH for that shyt now, but it ain't all bad.
'cause the common majority of Mainstream Rock acts know where the money (for them as individuals if they ain't caught up in 360 deals and deals that eat into their touring quid) is and that's touring.
Mainstream acts that ain't in legacy status like Tool, Metallica, Linkin Park (fukk Chester by the way) etc.. that can make money off they pedigree and release music WHENEVER it suits THEM, jump right into touring and stay touring. Hell, System of a Down was practically on a 10 year tour between their albums, stopping for a year, to put the music they made while on tour into the studio, focus on it, release an album, get paid for it and jump DIRECTLY back out on tour again. While they don't have the mainstream coverage alot of artists would definitely clamor for, they got steady bread off of tours, small moshpit like shows (God bless Webster Theatre in CT and Terminal 5/Gramercy Theatre in NY

) and alot of 'em know this shyt especially the record labels who often pair new fledgling acts that need more word of mouth/exposure, perfect example of what I can see of this dynamic being with the band Red Fang that opened for Mastodon around the time their first album came out.
Red Fang was barely known amongst half of the audience there but put on a damned good show, got good word of mouth, now they got they own following, doing steady touring and getting their own acclaim.
I'll wrap this up by saying Rock and alot of folk involved in it done took the focus off of being in the spotlight simply 'cause you had a band, one of y'all looked cute or you happened to score a catchy single 'cause you plagarized/sampled/got lucky (The band Jet with they ACDC garage sale riffs and the group Crazy Town with that HORRID butterfly song that some folk still don't know where it's from on some Puff Daddy - Come with me, shyt

).
Make a band, hit the road, build up show cred, work your way to the main stage, sign a record deal, keep plugging away on tour. That's how it is for Rock nowadays it looks like unless you got that Industry plant/machine shyt like some rappers do.