https://www.theverge.com/2018/11/27/18114194/microsoft-surface-pro-keyboard-thinner-design-patent-rumors

Microsoft has filed a patent for a Surface Pro Type Cover redesign that would potentially make it thinner. Spotted by WindowsUnited, the patent includes details about cutting or etching the Surface Pro keyboard to create a thinner version. Microsoft also appears to be exploring integrating the trackpad directly into the circuit board used for the keyboard.

Microsoft used to sell a Surface Pro Touch Cover, with a thinner profile and fabric keys, but the company has been largely focused on tweaking its Surface keyboard in recent years. The keyboard has been tweaked with minor improvements through the Surface Pro 4 to Surface Pro 6, and older type covers still work on modern devices.