I wouldn't think it would be that difficult for the souvenirs - it's another mesh over an existing object. (And frankly, I think they should be there with modular souvenir shops now in the game). The entertainers may be a bit more difficult - not sure if they can just grab the old models and update them, or if it requires a whole new 3d model and animation structure. Really hoping that they get some of these in the game in the next free update to go with the DLCs.