If KLM decides to partner with Air France and join Skyteam, this would most likely result in Skyteam and Wings consolidating into one mega alliance. Just imagine that. They would be unbeatable, with US fortresses at IAH, ATL, and DTW. European fortress at CDG, AMS, and FCO/MXP. This would also bring MAS and Eva Air into the picture, giving them a stronghold in Asia.
IAH (Houston Bush) is Continental's stronghold, not Northwest's. Detroit, Minneapolis, and Memphis are Northwest's.
Since CO is concerned, this is not going to be easy. They have a virtual-merger agreement, and a controlling say in NWA. Letting NWA go will leave CO naked, the largest US carrier without a serious alliance.