Like YouTube, Music could move to a navigation rail, though it would slightly limit the available horizontal real estate for browsing shelves (and anything under four tabs looks odd for that UI element).
Additionally, the image below shows YouTube Music retaining the bottom bar!
Maps for Android already has a two-column view, but an upcoming update replaces the full-width bottom bar for one that fits in the left panel.Check out 9to5Google on YouTube for more news:Be the first to learn about plans for Android, Google Plus, Google Apps, and more
20+ Google apps will be updated for tablets