Since Google has recently changed their logo and identity, the current banner seems a bit outdated - a style that was designed when the inset kind of subtle gradient look was used, back in 2013; especially on Google+'s logo which is probably where some of the inspiration for the current banner came from.
recently mentioned the idea of updating the banner and I thought someone else would take care of it. Since no one did, he came to me talking about how he thought it'd be cool if the Google "G" logo I made for my Simply Styled Icon Set was used in the banner (namely, the Google Folder icon, but also the Google alt icon I made which is directly influenced by Google's current logo).
Keep in mind that none of these ideas are set in stone, just quick concepts to get a few ideas across. We could use elements from any of the concepts - or any other ideas someone else has.
Banner redesign concepts: