I think it's complicated. First, the economy (despite what some factions would have us believe) is in the toilet. People are watching every dime right now.
TVs and Entertainment systems are hard to justify when there has been absolutely nothing new in nearly a decade beyond the size of the screen and resolution.
Smartphones and computers have gotten to the point where they're so good that the "average consumer" can get 8 to 10 years of use out of them, "prosumers" have more than they need as far as power and functionality and can keep a device for 5 to 6 years, and "pros" spend enough that they need to be blown out of the water with things that simply aren't in the cards very often.
In short, the tech-using world as a whole just doesn't have the need or is being impressed enough to warrant spending money on "updates" the way they used to. We want major upgrades and earth-shattering new features... and those things simply don't exist with regular frequency anymore.