Hmmm, I am a big rock fan, let me say that. But in fact, I am a music fan. If I hear what I like, I don't sit there and think whether it is pop or not. Are u2 a rock band or a pop band? They are big, and polished, and they use technology, so maybe they are a pop band. On the other hand, they "write their own music" and they come from a rock background, so maybe they are rock. Maybe in some instances rock music is pop music, by virtue of the fact that it is popular.
The Beatles started out as a pop band, in fact, you could easily look to them for the start of bands like nsync and backstreet boys. Now, they are remembered as being great. Hmmm
These are all random thoughts.
If people continue to listen to rock music, it will live. If they don't, then why should it continue to exist? If no one is interested in rock music, what is the point in it?
Music needs to continue to break new ground, to challenge the listener, to experiment, to push boundaries. That is what the great rock bands were doing in the 60's and 70's, but to continue to play that sort of music today is missing the point.
Why complain about modern music, because it is no longer dominated by guitar?
Why is electronica any less valid? If it is tapping into a youth audience looking for something new, then maybe it is the new rock music.
Now, I'm not saying there is no place for the past, in fact, looking back is always a huge part of moving forward. Music will stagnate though, if we all sit around dreaming of the halcyon days of guitar based rock, rather than think of what is relevant NOW.