Rock Band 4 owners are likely aware that the exporting process is somewhat slowly getting off the ground. One of the key elements of bringing a full last-gen song catalog over to the new consoles is allowing for on-disc songs from previous Rock Band games to be carried over. Now Harmonix is revealing some more details on how this is coming along, noting that the target date for Rock Band 3's catalog is around the time of the big December update.
The Harmonix blog points out that the Rock Band 3 export will go for $14.99 for verified Rock Band 3 owners, which is a similar price point issued for similar exports in older Rock Band titles. Harmonix will look to verify RB3 ownership through an electronic check to see if the owner has played the game in the past. It should be noted that Rock Band 3 will be leaving the Xbox Live Marketplace on October 30, so once that date passes, Xbox One owners will have to find and purchase a retail copy of the game.
The other on-disc soundtracks will be made available sometime after RB3, so don't necessarily look for those to be available in 2015. Once that's finished, Harmonix will turn its attention to Rock Band Network tracks. It should also be noted that Rock Band Blitz tracks appear to be ready for import now, so search out the Xbox Store and PlayStation Store. It's a lengthy process, but it's a small price to pay to rock.