Television is undergoing a huge time of change right now. TV news keeps losing viewers by the thousands, local news has become a joke, people can record network shows and watch them later, or just wait a day and catch up online. In fact, one of the major sticking points of the WGA negotiations was royalties for online efforts. Add on top of that the 2009 transition from basic analog signals for local networks to crystal-clear digital signals and you've got one big, ugly transition phase for TV as a whole.
On the one hand, this is kind of exciting, because there may be new, unexplored options for everyone to explore, on the other hand, changing anything that's big, such as television, will be a slow, clunky change. Will the majority of Americans still watch the majority of TV live in 20 years? DVR and online use keeps climbing every year.
I don't think TV will ever go away. But it may become like radio, where it is an established medium to get the same information you can easily get elsewhere. (Sidenote: Why is it that time-programmed recorders for radio are just popping up in more electronics now? I would have LOVED to have a "VCR" for my radio years ago. Or am I just noticing those now?)
Whatever happens, it will be interesting to watch and see.