Aaaand it looks like I will be spending the night in a hotel somewhere, or DB organises a taxi
The delay on my train has mounted, the connecting train is waiting a bit in Köln for some others (I presume the less delayed ICE 544) but not for my train (ICE 554)
I did the right thing - took the connection with the more generous changing time in Köln - and today that has backfired and left me stuck