With a bit of digging, we are told that it is a massaged Seaburg/Stoakley board with two sockets and four PCIe slots. If you look at the diagram for Seaburg, it only has 32 PCIe2 lanes, meaning that if Intel does not pull the proverbial rabbit out, there will only be four 8x slots.
Since it is PCIe2, that means you have the same bandwidth as a PCIe1 16x slot. This should be more than adequate for now.

Now this is obviously a high end box with lofty goals, mainly to be #1 in gaming. FB-DIMMs will add latency and bandwidth, good or bad depending on the specific game you are running. More importantly, they will add lots of money and power to the bottom line.
Cost is of little concern here. Intel is targeting the cost almost no object set, but the power is a bit more of a problem, especially as DIMM count rises. With any luck, this will be one of the first applications of Monroe channel idling tech to cut the power, and if we are really lucky, will get us to FBD/800.
In any case, what graphics will it use with those four slots? No clue because Nvidia says that this is wrong. I don't believe them either. In any case, this solves the biggest problem that V8 had, one GPU slot, and then overcompensates a bit. µ