Found that this will work and only produce 2 selectors:
```scss
//TODO: Cleanup placeholders when libsass supports nested selectors
%multimedia-display-none {
	display: none;
}

%multimedia-display-block {
	display: block;
}

.xxsmallview {
	.wb-mm-txtonly {
		@extend %multimedia-display-block;
	}

	.wb-mm-prgrss{
		@extend %multimedia-display-none;
	}
}

.mediumview, .largeview, .xlargeview, .xxlargeview {
	.col-md-1, .col-md-2, .col-md-3 {
		.wb-mm-txtonly {
			@extend %multimedia-display-block;
		}

		.wb-mm-prgrss{
			@extend %multimedia-display-none;
		}
	}
}
```