What's the criteria for something being a "real" competitor? This device provides functionality which is broadly comparable with the iPad, in the same way as m

What's the criteria for something being a "real" competitor? This device provides functionality which is broadly comparable with the iPad, in the same way as many netbooks, the Kindle, the Nook other eBook readers and a whole bunch of other devices. How comparable they are is debatable but are they competitors, in as much as is it possible that people will buy one of them instead of an iPad to fulfil one or more needs an iPad could have fulfilled. But how come this is a "real" competitor when the others aren't? If anything I'd suggest that the "real" competitors are the ones I can go out and buy and use now and where people are doing just that, rather than an unlaunched device I'd need to mod.