iTunes is used, overwhelmingly, to deliver music to mobile devices. And streaming is facing a number of serious barriers for that kind of mobile use: battery drain, network coverage, bandwidth caps and the high price of data plans (with sufficient caps).

So, almost regardless of individual quality, streaming services are not replacing iTunes any time soon. Almost certainly not in the US and likely not anywhere else.

They definitely have a market, particularly in competing with terrestrial and satellite radio. But streaming is simply not a good fit to do what iTunes is used to do.