I like how Mission Impossible typically feels like old fashion film making, but Marvel usually doesn't. It isn't a knock or anything, but the Mission Impossible series has been hitting so many home runs lately, it is a better and franchise in my opinion than James Bond.
As for Black Widow, it will be interesting to see if she can carry a movie on her own. If they emphasize the spy elements, the lore, and world building, it will work because it will be truly about Black Widow's character. If it is just an action movie with a mission then I don't know what to think. It was kinda silly and annoying the idea of the big fight between the two sister and find out they are sister. Like, I don't know who writes this stuff, but that is just stupid.
You know what would be a better scene, them actually talking, but trying to assess if the other is trying to kill them or not. Like Black Widow's "sister" is doing subtle things like positioning herself to have an advantage IF they fight, or trying to poison her and Black Widow is quietly countering the situation because she is just better at it.