About the PC Vs. PS4 discussion. What is important for a console is to use the latest technology they can that will be affordable and can be made more affordable over the years as well as power consumption on release and gaming performance.
What the PS4 has over most gaming PCs out today should be faster loading times (Assumption) with the fast GDDR5 unified memory. It will be interesting to see the impact it has for Intel and Nvidia between 2013-2016. They may have to go onboard with HSA. AMD will most likely be very happy getting the deals they have done with the big players in the console market as all games will be designed to make use of their architecture a lot.
The graphics card in PS4 seems ahead in architecture than anything AMD have released so far in desktop market which is important for a console. If Sony waited a year, then they would most likely be able to fit something similar in performance / powerfuller than a GTX 680 but they are also thinking about the future with the current decision.
Hardware improvements will take a long while to get much more more power to be worthy of a new console, we are talking at least as long as current PS3 generation will have lasted before successor launched. Profitability can be increased enough with current design in future while being fit for purpose in its life cycle. A die shrink is around the corner for the PS4 so in a recession, they can be competitive in pricing not only at launch but much more in the first 2-3 years while being a profitable console. If they waited a year, they would have lost quite a bit of money in both short term and long term for slightly more richer graphics and a console that will be less eco-friendly in its life cycle

. While PCs will most likely always be more powerful than a console at launch, it is more about the technology being cutting edge at the time which is important. You can always build something like this if you have a lot of money:
http://www.top500.org/system/177975 , that argument I think is a bit silly, what is important is the technology being latest, affordable, power efficient and fit for purpose going back to my original point.
About performance top graphics games will use on PS4 at initial launch, I would guess like probably about 100% of GPU and potentially most of CPU with more than 50% ram being used. It should be easy to max out console but all the improvements in future will come in optimising everything for the hardware by improving all artwork and techniques to maximise architecture for games benefit.
About how PS4 might look like, I think they will probably go probably for black colour and might even go for something similar in form factor to this but slimmer:
What I like about the PS4 as I mentioned in a previous post, most of frustrations in gaming seem to have been eradicated with a lot of wants being fulfilled. I wonder what surprises are left in store for PS4 as they are still deciding on stuff.