Braces can be used in many cases, but `case` keyword is used only in `switch` and `match` and is not ambigious. You can see what construct it is from the first word.

I suspect the example in the proposal refers to an object that doesn't match any of the previous options, but is still an object.

For a default I'd expect there to be another pattern.

The default pattern is a variable name.

> [About variable name patterns binding to the name] Eliminates the need for an else/default leg, because assignment to any variable will be sufficient. JS programmers are already used to assigning variables that are then ignored (in functions, in particular), and different people have different tastes in what that should be. _, other, etc, would all be perfectly cromulent alternatives.