Television is an ephemeral medium. A huge amount of effort goes into producing something that will only be seen once and is unlikely to be played again. Indeed, with the advent of reality tv the medium is becoming even more consumable in its outlook. Reality shows, news and many documentary strands are temporal and make poor material for repeating (of course, I Love Lucy and Dad's Army are both accessible on some channel no matter where you go in the world, so some content does survive).
Many of the shows have been captured onto tape and filed somewhere in the broadcaster's library, but remained inaccessible to the world at large. Others have simply been and gone, and we have no idea of whether things that will be important in the future have been lost.
It does beg the question of how skewed our view of the past is - it's easier to consider what has survived as being predominant, just by virtue of surviving; therefore those who built in stone get most attention from archaeologists. Will the same happen to TV?
The falling cost of storage and the advent of TV over IP is resulting in much, much more content being captured and made available for repurposing, and possible kept for posterity. An excellent example is the Pathe Library.
In a medium that is barely half a century old, it seems strange to talk about archaeology, but perhaps there will be programmes on television that are about digging back not in the earth, but digging back in data.
The Wayback Machine already does this for the internet, as do search engines like Google, of course.
We might all feel that we're at the leading edge, but it's fascinating to think of what the future will make of what we're doing today.