So there's several different questions here:

* whether machines will be capable of composing some kind of appealing music. This is already possible, and likely to get better/broader.

* whether machines will get so good at this (on demand, no less) they will crowd out contributions that are largely human-crafted. This seems uncertain to me, maybe more likely at the commodity and conceptual ends of the market, maybe less so in craft-niches.

* whether music is really a personal experience or a social one -- or, since it's obviously both, to what degree people want both things when.