Emir among new features I would like to see new UI as this one is already too stock and boring as almost did not change sice years...
Other than that would like to see the small apps back, Radio back, Widgets back +more widgets, improvements to camera and abandoned 4K recording, panorama or effects modes. Lock screen widgets back, Xperia keyboard back, notification rings back (Signature), app2SD, better performance (no lag) and battery.
More new features would be welcomed and nice surprice.