1080p graphics support

Hello,

Typically we prepare splash images in 1280x720 for HD and 720x480 for SD (0.91 PAR). Since Roku also supports 1080p, do we need to create the splash image in 1080p now? Similarly, how does this affect the overhang banner? Typically I made it 1280 pixels wide. But of 1080 is supported, do I need to go with 1920 pixels wide? Or are all the UI elements still just 720p?

Thanks