Not sure about your question. Analog audio is the only option on most of the consoles on your list. If you want sound, you have to use analog audio. The only consoles that offer a digital audio output are the PS2, PS3, and XBox360. Those three can provide multichannel audio via Dolby Digital 5.1 audio. Except for those three, all of your audio will be stereo at best. Some (such as the Wii) will include decoding cues for Pro Logic, which provides a way to get "intentional" surround sound from those stereo sources when you apply Pro Logic II processing. For others, you will be using a matrix surround processing mode such as Pro Logic II or Neo:6 to get surround sound from that stereo source.


Composite is certainly around solely for compatibility purposes with older or more basic hardware. The only source I have which can't offer any better than composite is our daughter's LeapFrog. Even my VCR is S-VHS, and thus has an s-video output. Of course, when we're discussing hardware from the 1990's or before, composite is pretty much king: s-video was very rare and component was outright unheard-of until late in the decade.


S-video is fading rather fast, mostly because the gap between it and the more ubiquitous composite is so tiny when compared to HD connections that we're all starting to use. S-video can not do HD resolutions. It can't even do 480p. Like composite, it is limited to 480i (or 576i if you are dealing with PAL, which I doubt many of us are).


Component will be around a while, although there are efforts by AACS to kill it because it is the only widely-used analog video connection that supports HD resolutions. AACS has a phase-out schedule that will first restrict component to 480i and then delete it from hardware entirely for any source component that uses AACS encryption (which at present is just Blu-ray, pretty much). Because it's analog, though, it's already becoming less widely used than HDMI.


SCART is a European entity. No presence in the North American market, and thus not on Outlaw's radar.


Sony and Microsoft will focus their attention on HDMI output. We'll see what Nintendo does, since they felt no need to even put an optical or coaxial output on the Wii. I agree, though, that nobody is going to revise existing non-HD platforms or discontinued platforms to offer HDMI. It would be an utterly pointless exercise with no practical value, and it would be pretty expensive.