I think it would be awesome if at least before the encore of a career we could do a cutscene to bring even more hype to the last song in the tier. Like how in GH:WT it would be used to introduce celebrity guests or in GH3 it would introduce who you were going to battle next.
I could also see this working for people who use their songs to tell a story, as it gives them more freedom rather than having to cram everything in one cutscene between tiers. I just think it would give careers even more personalities and possibilities!