Recently overheard, from a pair of student composers chatting: "Arpeggio? Philip Glass so OWNS the arpeggio!"
I recognize the sentiment — it's widespread enough that the arpeggio-heavy theme music to the TV series Fringe was instantly pegged online as faux-Glass — but still, if that's the case, that's a major piece of musical territory to own, at least on par with Ted Turner's two million acres and share of the North American bison herd, and also something of a limiting factor for others writing tonal music.
Which made me wonder... if all existing music were wiped from the planetary memory, and you could stake a trademark claim to any one musical element or figure, strictly on the basis of its income-generating potential, which would be the most potentially lucrative by locking others out of your territory? A major triad? An authentic cadence? Common time?