It would take some serious work to get into vectors, plus it would be a challenge to handling them in such a way as to achieve the loading speed of Flash but without the totally BS way that Flash did it (as in ungrouping something and ending up with a bunch of fragmented strokes, etc.).
I'm just a Hype customer, but for my three cents, I'd place loading performance at the top - the ability to have total control over loading regardless of scenes, the ability to display content without waiting for off-screen content to load, the efficiency resulting from a shared resource folder for all Hype content (including consolidation of JS without all the repetitive code - run Google's analysis tool and you'll see this flagged).
The biggest problem from the marketing communications perspective is skyrocketing bounce rates. If a person has to wait for more than two seconds before they can get to it, they will jump away. (BTW, see the topic on compressing JPGs and PNGS. This is a big help.)