Apple very well could move into the gaming world, They could get a good deal on Intel i5 or i7 cpu with decent Nvidia GPU that could kick ps4/xbox one but if they wanted too.
This is a fun game of "make a cheap gaming PC that is better than next-gen consoles".
As a reference, the GPU in the PS3 is almost exactly the power of a Radeon 7770, and the Xbox One has a Radeon 7750. Checking NCIX I can find a 7770 for $119.99 (with free shipping!)
The AMD CPU in the next gen console has a lot of cores, but each core is a very slow core. They're better than Intel Atom cores, but not by much. Each core in a Ivy Bridge processor would be "worth" about 4-5 of the AMD cores going into the consoles, so a dual-core Core i3 would be more than enough to slap around the CPUs in the Xbox One and the PS4 in almost any scenario.
The memory in the PS4 is GDDR 5. This means it has very high bandwidth, but is extremely high latency. For certain applications this is good (e.g. video cards), but for more general purpose code this is a very bad thing. This is why high-end PCs don't use GDDR5 for system RAM, and only video cards use it.
But since the next-gen consoles are a unified memory architecture they needed to go with one or the other. So, in the PS4 the CPU took the hit so that the GPU benefits, and in the Xbox One the GPU took the hit so that the CPU benefits.
I guess this is another way of saying not to worry about not having GDDR5 in your gaming PCs system memory, for almost all the code running on your PC (including games) DDR3 is superior, and the graphics card can have its GDDR5. Best of both worlds.
So, when we do the math we get something like this:
CPU: $130 Intel Core i3-3220
Motherboard: $96 (GA-H77-DS3H)
Memory: $90 (8GB DDR3-1600)
Graphics: $130 GeForce GTX 650 Ti (faster than a Radeon 7770)
Storage: $70 Segate 1TB 7200RPM drive
Case: $60 Corsair Carbide 200R
PSU: $50 Corsair CX430M
~$640 worth of parts. It is faster than either next-gen console, but there it doesn't include any game controllers. Also, the Xbox One has the Kinect, which isn't something we can replicate right now with PC parts. But I would have no reservations putting this up against a PS4.
There isn't a tonne of margin on this gear, so I figure it would cost Apple about $500 to put something like this together. But then they would have to sell it at practically zero margin, which is very un-Apple like.