I think Apple TV is already in the process of disrupting TV, if I recall disruption theory correctly the disruptor is not quite as good as the current status quo.

Let's look at apple tv compared to a traditional cable box: Netflix is pretty good but doesn't have the same level of "appointment" or "water cooler" shows as cable. Cable is far superior with live sports, apple tv just has MLB streaming with probably the NBA and NHL soon to follow.

Already for some audiences that might be enough to kill the cable bill entirely or (more likely) to reduce the package they have. Throw in the fact that it can also play the stuff that's on the your iPhone or iPod, has built in pay per view mechanism, and a prettier interface and I think you might have some freaked out cable/ satellite providers.

Apple TV is definitely not as good as cable but it's getting close to being good enough.