No way. The X6 is far too impractical to obsolete the X5. It may eat into the X5's sales a bit initially, but once people see what a vanity purchase the X6 is the X5 will be just fine. CLS cut into E-Class sales at first and then dropped off while the E picked back up. Same will happen with the X5 and X6. X6 will sell on looks, both inside and out, better engines and most importantly a more connected driving experience. X5 will sell on cheaper price (relatively) and much better utility relative to the X6.

M