Cologne has major insurance and media companies with China links and Duesseldorf 50 kms away a bunch of European/country corporate HQs ( Vodafone, Nokia, HSBC Trinkaus & Burkhardt etc. ). And not to forget the Telekom HQ in Bonn.
Should make some impact as DUS has no Asian longhauls at all. Nearest competitors are AMS, BRU and FRA.