If I may be so
sweeping:
ridiculous. People could no more run out
music to play with the
twelve-note scale than they could run out of
stories to write with the twenty-six letter
alphabet. If music sounds like it's reaching a
threshold, it's because the
mass market for music
emphasizes popularity over
creativity.
As for E2 running out of nodes: well, there are always new ways to arrange the alphabet.