RAW formats can/usually have a thumbnail/preview embedded. I convert all of my Nikon RAW files to Adobe DNG (Adobe's RAW format) and I have a Leica camera that uses DNG natively. When I convert, I can chose to have a full-sized preview embeded. This makes certain software give a faster preview.
Sorry If I’m misunderstanding something, but aren’t both of the things you mentioned already a reality? I thought RAWs included jpeg already, and Bridge already has an option to prefer that.
