nothing to do with exchange rates or oil prices. Memory traces, especially when its an onboard memory controller, have to be as short as possible, with the memory controller on a chipset you get a little leeway as essentially it works as a signal booster so you can deal with power ciruitry easily around the socket, send memory traces to the northbridge and have a clear path in the top right of the board for all the mem traces.
On board mem controller without a signal boosting north bridge is one problem, the fact that its triple channel adds to this as the trace number went up significantly aswell as the initial problem with mem controller.
This all adds up to signal strength, interference problems and literally a lack of space, meaning you need a higher layer board for more tracing area and thicker/more copper layers to insulate the signals from each other. It means a triple channel board can not in any way be the same price, and never will be the same price as a dual channel board. Frankly the chipset, P55/x58, the chipset does a heck of a lot LESS than they use to do, probably smaller pin out, smaller die, less complex, cooler running, easier logic all due to lack of mem controller, infact massively smaller pinout due to no mem controller. The chipset should without question be cheaper than a X48/p45 due to this, all the cost is in layers and complexity of the board.
Dual channel lynnfield versions shouldn't have any problems being cheaper and similar to current board pricing, though the lynnfield cpu's might not be "that" cheap due to same reasons, pinout and mem controller onboard adding cost to the cpu's over a C2Q.
I doubt anything significant will come out on s775 now, it would be rather pointless. they have the range of speeds covered, coming out with a higher clocked 775 isn't particularly likely and as for whats currently available, a Q6600 can still get up beyond 3.5Ghz , is stupidly cheap and quick and is more than enough for any games/general use so for your general home user new things aren't going to offer any improvements.