Assumption 1: Sony will cut the price (soon)
Assumption 2: Microsoft will not respond to this move
Assumption 3: Microsoft will continue to do nothing until their lead has eroded entirely
Those are pretty damn big assumptions considering that Microsoft and Sony have both proven time and again to prefer the opposite. Sony doesn't want to reduce the price and Microsoft does whatever it takes to keep the momentum in their favor.
Ockham's Razor Says: "Both companies will continue to behave pretty much the way they have been and Sony will lose the Console Wars this generation."