I need a configuration which would beat every upcoming game until 2015.
My budget is around $1600 USD.
You can build a really descent machine for $1600, today in 2010, but not one that will attain the goal you're after game until 2015.
However there is a difference from just being able to play a game, to being able to maximize and take advantage of all the game has to offer, in that respect $1600 for an entire machine monitor and all, may struggle to get you there today with games like Crysis.
But that does depend on your gaming intentions as monitor resolutions you plan on running, eye candy you want to be enabling in the game itself, Etc.
We'll see some major hardware changes between present day and 2015, we'll see game developers change hands, some go under, and possibly some new designers to the market, all trying to design to take advantage of newer hardware.
The best you can hope for is a system viable enough to get you through next year and even that will probably cost more than $1600 for an entire machine.
So can you set your sights lower, to make helping you a possibility and not an impossible dream?