I’ve seen some people saying how they want Keith to wear the full Blade of Marmora uniform/armor and I think it might actually happen. When Shiro disappeared he just left his bayard, not the black paladin armor. So if Allura or someone else does become the red paladin they would most likely take the paladin armor as well, leaving Keith with no armor. Thus he could start wearing the Blade of Marmora armor which would be really cool to see!