The next 3-5 years will be very interesting.
Nobody is invincible, look at Sony or Nintendo. Samsung are catching up.
Apple need that 'killer' product to spur their growth. Always have. Steve is no longer around to concieve that product. Jonny Ive's designs are not cutting edge anymore. Apple is too pricey for the Asian market.
Where to next after the iPod, iPhone or iPad?
Apple need to build on their innovation, be more flexible, quicker to market with upgrades. The iPhone tech is famously 2.5 years old. Where is the new Macbook? or iMac?
If this Apple TV fails in could be downhill from then onwards. Brands can be destroyed just as quick as they are built.
I will leave you with one thought:
Ping.
An Apple designed Car or other kind of personal vehicle is likely still on the drawing board somewhere. Google is working on this (self driving car) and It wouldn't be too far fetched to think there are people at Apple doing it to. When was the last time GM or Ford came out with something everyone wants. The innovator in the automobile field right now is Toyota. But cars today look and function exactly like they did in 1992, and the only innovation since then is the Hybrid.
The iPanel/iHub or whatever the pundits think the Apple TV is going to be, has to do something innovative and last 7 years. Look at the existing TV-like things we have, the iMac and iPad. The last innovation for televisions was "3D" and nobody gave a care about that feature. I'm going to argue because like the "If you see a stylus you're doing it wrong" argument, 3D glasses is doing it wrong. 3D has to work without glasses, from any angle, and not give people a headache from eyestrain. Nobody's cracked that nut, and the Nintendo 3DS's 3D is barely effective.
Nintendo is the innovator in the game console field, but they never make the mistake of subsidizing the console, unlike Sony and Microsoft. Unfortunately the cost/fun return on a Nintendo console is rather low, you might only buy 5 games over the life of the console, and those will primarily be Nintendo properties. They're exactly like Apple, they make their own hardware and software and don't licence anyone else to build hardware that can run their software. Anything you build for the Xbox 360 can be ported to the Windows PC by changing the build target, but the Xbox 360 has also been holding back Windows games because that's where the money is (consoles.)
So it's pretty hard to argue that Apple can't make anything new when they're already attracting software developers to their cheaper ecosystem and similarly priced hardware. (An iPad2's current price is 399 versus Xbox 360's launch price 399$.) A TV could replace the living room game console, the television, the cable box, blue ray player, and the audio/speaker system, stream netflix and rent new releases. Right now the Xbox 360 and PS3 can do some of this, but not very well. I could imagine a television coming equipped with some kind of wireless 7.1 speaker system. Eliminate about 10000$ in hardware with one device.