I don’t believe that the question is valid per se. I don’t think any type of music truly “dies”.
Look at classic orchestral music, which I think is a good comparison to rock. A lot of elements from this type has made it into many “other” types of music, and rather shaped some of them, even. I think that the same sort of re-use of musical elements is happening from any and all types. So while “traditional” rock may not exists (and I mean in the same force and reception) in the future, everything that’s been recorded and re-used will of course live on, but new material in the same genre will not be as significant.
So I believe that just like there are people still in the classic orchestra scene, there will be people continuing the rock scene, though not on the same scale and with the same appreciation, or popularity.
I mean, music in itself is pretty generic, meaning there’s only so much “data” in the field of music and the (at any one time) currently “popular” type uses only so many combinations as is necessary.
Everything all around is is cyclical, and if you look at pretty much any art, this is true as well. The same type may never again be created (for whatever reasons) but bits and pieces will be borrowed for new types.
Instruments, styles, rhythms, chords, progressions, scales, etc. go in and out of “style” every now and again. And with all the combinations possible, so many new types of music will inevitably be king-of-the-hill as the tribes of our planet continue to produce music.
So is “Rock” in trouble? (Of course, this would depend on the definition of “trouble”.) But no, it’s not in any more or different trouble than any other type of music ever was, I would answer.
But of course, these are just my (and I saw others in the thread with similar) thoughts.