Silly. Of course they will be compatible. Have you seen how many third party cases have MagSafe? That’s a bit more of a engineering challenge than a capacitive button. There is absolutely no way there won’t be hundreds of third party options available day one which work with the buttons no problem whatsoever.

This all makes a lot of sense. Reading the post it is just replacing the low power mode on the existing processor with a separate even lower draw one to handle the emergency functions like “find my” and Apple Pay with a dedicated chip. Makes sense.

Considering how apple handled the solid state home button and track pads I have faith solid state volume buttons will be fine. Less movement introduces fewer points of failure too. In theory.