Modal Keyboard
just a thought
Consider text editors: we tend to want to issue commands to the editor for more than just "insert this letter at the cursor" or "move the cursor up/down/left/right". Looking at keyboard-driven editors, there are three main ways we can accomplish that: dedicated keys for functions (F-keys), function layers on our standard keys (keyboard combinations), and different modes (insert mode, visual mode, etc).
What if we took that idea further down the wire towards the user? What if our keyboards had modes instead of layers? Most English keyboards have at least 2 layers accessed by the shift key (and sometimes caps lock). Some English keyboards have the ability to type non-English letters/characters via modifier keys, thus using the keyboard combination method. I propose that there ought to be a keyboard that is modal. For example (for a typical English user) it would begin in English mode. By pressing the mode-command key (Perhaps the only special key that wouldn't be passed to the computer), the user would be able to type a mode that they'd like to switch to. This mode-command key would be analogous to Vim's escape key. To improve the usability of this kind of keyboard, it would make sense to have a small display to indicate the current mode and the currently-being-typed new mode.
I know some layer-based keyboards take this screen-based approach to displaying the current layer, but they tend to use either raise/lower layer keys or keyboard combinations to switch layers. Once we have keyboards that can type in a few modes, we can consider modes other than what we would think of as standard in a keyboard. These could include (off the top of my head) a mode for TOTPs (enter the mode via the mode-command key, then type the name of the service of your TOTP, then pressing enter would result in the TOTP code being typed to your computer. Perhaps even a fully fledged password manager could reside in one's keyboard.
The possiblities are endless if we question that which we consider standard!