The question is what is wrong with using your tablet only for Netflix and Facebook (which stands for media consumption, ie, video, audio, reading, and light Internet usage, ie, 'web surfing', short communication). I think there is nothing wrong with that, except that Apple might have increasing trouble selling their tablets at their current prices.
The question is how large the niche is for applications beyond consumption and light communication that work better on a touch-device (eg, because they don't need a desk) and better enough that they warrant getting an extra device for that (including getting data on and off that device) compared to getting a dual-use device. That niche certainly exists and is growing but again, maybe dual-use devices will be the one serving it in the end.