I would see support of all argument kinds support in any proposal for a new callable: positional only args, named args, keyword-only, *args and **kwargs.
The exact notation in probably less important than missing functionality.
Hm, but using Protocol you can already express every callable type. We could duplicate all of the complexity of 'def' parameter lists into the type notation, but it would be very complex. So this requirement is at least debatable (I'm not actually sure how I feel about it).