Just announced by Harmonix earlier today, delistings for Xbox 360/PS3/Wii have already started on the European PlayStation Network as of this post.
“We have an important Rock Band Network update to share. Unfortunately, ALL RBN songs on ALL legacy consoles (Xbox 360, PlayStation®3, and Nintendo Wii) will no longer be available for purchase from the Rock Band Music Store beginning later this month. As with other delisted content, owners can continue to play previously purchased RBN songs as desired. These songs were never available for purchase or playable in Rock Band 4. All songs available on Rock Band 4 are not affected, regardless of source.”
Keep in mind this is only related to community released DLC and not Harmonix released DLC. Want to keep your library strong? Start downloading now just incase you aren’t able to in the near future.