I'm sorry but they have a defacto monopoly in the digital music market. When Walmart, Amazon and Microsoft specifically target you and can't even get their foot in the door that says a lot.
As far as the term. I mean, I understand people can have different definitions but the reality to me is when a company feels they can abuse their customers without fear of them going elsewhere that means they have reached the point of de-facto monopoly. Apple has no problem taking functionality from their own iTunes customers to kill the Pre and that to me is the line (though I fully understand others can differ)
The other problem is that no other companies who might stand a chance are really trying - if a huge techno-music company such as Sony-BMG made a proper attack, such as "our entire catalog, open, for $X/year" and that went nowhere, then I'd start to be convinced.