LCY-DUS
The route has always been served by an ATR42 turboprop, first by EAE, later by Lufthansa. So not much change if a Fokker 50 would take over (VLM used to serve nearby MGL (or "Düsseldorf Express" as it was called) from LCY for many years.
Cityjet's applications started before the VLM take-over which explains why they always specified the RJ85 in their applicatiions. If they are awarded slots, they can, of course, use any aircraft type they want.