I think analog video outputs and inputs are going to be available on consumer equipment for a long, long time. Even after the transition is made to DVI & friends, you'll still have lots of "legacy ports." Look at how long ISA and PCI coexisted in the same chassis, before ISA disappeared.

Even after stuff stops being manufactured with legacy ports, I'm sure you'll still have dongles and converters and things like that for a long time.

There'll be a reduction in quality, of course, but no more than you're already seeing with all-analog rigs.