In an earnings call, Activision Blizzard CEO Bobby Kotick noted that he expects Xbox One and PlayStation 4 installed base to grow more quickly than their predecessors as both Microsoft and Sony are prepared to cut down their prices sooner than usual.
According to Kotick, there are "lots of efficiencies in manufacturing that could drive hardware prices down sooner in the cycle.". As a result, "there's no indication from our perspective that you're going to see anything other than a very successful 7-8 years."
For the soon-to-be last console generation, Xbox 360 received its first price cut two years after launch while PlayStation 3 received its first price cut after 7 months, but only because consumers weren't buying it at its original $599 price. This time around, both console makers are using off-the-shelf components, so they should be able to reduce manufacturing costs more quickly; then it would be up to them to pass on those savings to consumers.
