Everything is a bubble to some degree, everything that has a gold rush to it. Affiliate marketing is a bubble. As soon as consumerism goes to shit that's when the shit really will hit the fan.
A bubble is an expansion in the price of a commodity where the rate of expansion greatly exceeds the normal rate of price growth, often as measured by the inflation rate. Affiliate marketing is an activity, not a commodity, and it doesn't have any sort of price attached to it. So, wtf are you talking about (you obviously haven't a clue).