Flat UI is not the only way forward

Max Rudberg has a well-reasoned and moderate article on mobile design.

The hardware and UI have different roles to play. The hardware is constant, not changing, and should take as little of your attention as possible. This goes perfectly in line with what Apple are doing; reducing the hardware to a minimum with clean lines and invisible seams. As technology gets better, the hardware gets out of the way even more. The hardware sets the stage for the user interface, and its content, to shine.

When you launch an app on your mobile device, the device essentially becomes that app. Screens are great at drawing fine details and subtle gradients. Its part of a UI designers toolbox to make use of textures, shadows, light effects, etched or embossed elements and so on to make the UI tangible and understandable. I don’t see them going away.

Like all types of design, opinions about software design are easily influenced by fashion. Some styles go in-and-out of fashion, but after many years they persist and are recognised as truly great. This is what I think is Apple's philosophy.