Fox Kids ended because Disney purchased Fox Family Worldwide. Due to several factors in the deal (like gaining the Saban library and access to international Fox Kids channels), it meant that Fox Kids would not be able to last past the 2001-2002 season.
Fox has not had a saturday morning block since the end of 2008 (when 4KidsTV ended), and they've shown no signs of being interested in a new block. If they do, then okay, but saturday mornings (especially on broadcast television) are on life support; there's just no money behind it anymore. And even if they do make a new Saturday block, it won't be a revival of Fox Kids (unless Saban takes a sudden interest in returning to Fox).