interesting, in that case they will only be able to run 2 units in multiple.
Probably one from Frankfurt and the other from Dortmund or Hamburg, maybe calling at the usual Ruhr stops on the way
According to the most recent issue of
Modern Railways, we won't be seeing them just yet - the revised rules still state that trains must be a minimum of 375 metres long* (the distance between two 'escape' doors in the Tunnel), and the trains in question must be through-gangwayed.
However, this may be subject to change if the shorter trains can be proved by the operator to be safe for evacuation nonetheless.
*An ICE3 is 200 metres long.