It's definitely not that they can't. But, if they don't change it after 1.18, that would seem a little weird. Mojang shouldn't slack on things as simple as some textures in a scene that they probably have archived and can edit at any moment in whatever programs they use. Minecraft is revolved around updating, meaning Mojang should be prepared to actually and fully update what they're changing. Cause if they don't, I'd hate to end up with an outro decades old that has barely anything recognizable from the current game.