In this case, New York's redistricting is going to be controlled by Democrats who will be trying their damnedest to eliminate either NY-23 or King's district in Long Island [much harder]. The Democrats really don't technically lose too much in the long-term by losing NY-23, it's mostly just symbolic and kinda funny how bad the GOP is in the Northeast.
You're assuming- perhaps wrongly - that the Democrats will control the NYS Assembly, Senate and Governorship after the 2010 elections. They almost certainly will control the Assembly and probably the governorship (assuming Paterson doesn't somehow survive a primary), but the NYS Senate is still closely contested. Republicans could retake control in 2010, even if a Democrat or two doesn't try to stage another leadership coup in between now and then.
