I believe the right question would be: why would MS let Sony take that big advantage? They can perfectly go for the same route.
It depends on many things.
I can see Sony offering a pretty "core" naked system, that's my hope.
Ms can subsidize more but they have to include Kinect. They have to deal with the overhead induce by running a Windows 8 renditions (my bet is that feature wise the xbox will not be in the same ballpark as the ps4). All comes at a cost.
Then FLOPS is by far not the only important metric to measure GPU power. Nowadays Nvidia and AMD FLOPS are really close but still before Kepler Nvidia was doing better with significantly less FLOPS than ATI.
I would say that the most important metric for GPU might still be
fill rate with blending.
If I go by this
review of the gtx 680 putting every other metrics aside one may notice that the real world performances pretty much follow the fillrate with blending performances.
By looking at this graph only you could almost tell how those GPU ranks in real world, FLOPS don't.
So definitely the memory architecture is critical. Say Sony has standard solution with a pretty wide bus on GDDR5. If MS has some on chip memory pool and bandwidth to it, well it may trump FLOPS.
Then there is the overall system performance. MS may have more CPU power, more RAM, and lower latency RAM (DDR4). Definitely it's going to make a difference. (I go by the rumors even though I agree with SHifty it's pointless at this stage).
Anyway I think it's pointless to compare both systems at this point, let see the price, the overall software environment, which accessories are std or not, and then the real specs.
At this stage that focus on comparing systems gives a F-B smells at this thread and that's not the place here overall and not the purpose of that thread as Shifty pointed out.
Better move foward imho either I predict a tropical storm level of thread cleaning to follow...