Brand New
 Manchester Orchestra
 The Doors
[X] CCR Masters
This is your baptism.
Marilyn Manson - "The Beautiful People"
Weezer - "Island in the Sun" or "Beverly Hills"
Talking Heads - "Burning Down the House"
Avenged Sevenfold - "Beast and the Harlot"
Blue Oyster Cult - "Godzilla"
This'd be a good game for a few bands to make a comeback:
B-52's - Rock Lobster
Devo - Whip It
Kiss - Rock And Roll All Night
The Mighty Mighty Bosstones - The Impression That I Get
The Go-Go's - Vacation
Also, I won't make specific song guesses, but here are some bands that seem likely to me, based on the sort of songs they produce:
All-American Rejects (Swing Swing?)
Barenaked Ladies (One Week?)
Journey (Separate Ways? Stone In Love? I dunno)
R.E.M. (It's the End of the World as We Know It?)
Freezepop (Science Genius Girl?)
Also, while not a returning Rock Band artist, Joe Esposito's "You're The Best" (from The Karate Kid) would be a great fit for this game
Actually, seeing the way things are working with that setlist, combined with the way it'd work with RB2:
B-52's - Rock Lobster (We've had a semi-confirmation of more of them, it's an incredibly recognizable song, and pretty fun to play)
Blue Oyster Cult - Godzilla (It's, again, one of their most recognizable songs, and would finish off a tour challenge as their third song)
R.E.M. - (It's The) End of the World As We Know It (Seriously, I hate to use the "very popular hit, not yet in RB, would round off a challenge" card, but it fits SO WELL with SO MANY SONGS)
"They're goin' ta have to bury what's left of ya in a soupcan!
Peter Gabriel- "Sledgehammer" - a popular song by someone who hasn't been in RB yet plus they could have construction workers breaking blocks with sledgehammers.
Weezer- "Island in the Sun"- I would have guessed Pork and Beans would have been the Weezer song for this game but it came as dlc. There are plenty of lego sets that involve palm trees and boats so they could incorporate that into the background.
Sammy Hagar- "I Can't Drive 55"- Im not sure if there is already an opening song for this game but it would fit with the car openings the regular rockband games get.
The waiting, for sizable Tom Petty DLC, is the hardest part.