OK, I admit - a bit of a troll:
I'll go out on a limb here and draw a parallel between Combocams and All Season Tires!
A 'good thing' perhaps, but if you compare the top-end of Stills equipment/Summer Tires to top-end Video equipment/Winter tires, the hybrid beast of Combocam/All Season Tires is pretty shabby by comparison. Too much compromise is needed for the hybrid to compete in all areas with the real thing. Something is bound to be left behind. Both ComboCams and All Season Tires scream COMPROMISE. But - they do do an admirable job given that compromise.
We are at the stage where technology allows the creation of good HD Video in Stills cameras and, perhaps to come in the future, is the reverse - good stills in Video cameras.
But I think the arrival of stills equipment that shoots good video might actually have talked up the stills market into thinking it wants such a thing. The disciplines are different in approach and execution. Yes, I know we may want shallow DOF in video and stills has given us that by happenstance - great! But stills cameras are still hopelessly handicapped to shoot good HD Video & Sound as effectively and efficiently as a good video camera. The physical form factor just simply creates too much compromise. Just look at a DSLR kitted out to shoot good video.
Yes, it would be great for studio guys to shoot with just one box and one set of lights - but I wonder if Panasonic may not be showing the probable way to the end of this discussion. They have just brought forward the combination of a really good Combocam in the GH2 and they are about to ship a superb Video camera for around $5000 - the AG/AF100. Both the GH2 & AF100 use the same lens mount and therefore have interchangeable glass. Hooray! That means only one set of lenses. And similar abilities for relatively shallow DOF - the same +/- as 35mm motion picture.
But if you look at the video goodies that come in the AF100 and you were to try to cobble those additional features onto a stills camera, I believe you would have that All Season hybrid that was OK for many but not so much for the top end: an All Season ComboCam.