You really need to keep composite, too many legacy products out there not to include it. Many times I use composite just used for a temporary hook-up so it is a matter of convenience. I would drop S-vid and component.
-Bob
I would make a different set of choices, in that I'd keep component (my kids like to play the Wii, for which I have a component cable. Also, since switching between S-video and composite can be done with a 3 dollar adapter, I'd drop the composite and include S-video instead. That way older formats have at least the option of the best possible signal path, which is precluded if you only allow a composite connection for them.