I heard the same. All hotels are usually booked up by now, and then it sorts itself out in March or something.
That being said, there is some kind of fair in DD as you say, so maybe satying in Cologne will be better. Also looking for private accomodation is possible.
I will hopefully get my tcikets through OGAE Norway, and don't need to worry about tickets sales, but getting a t\ticket for the final shouldn't be so hard. I know this year, they still sold tickets on SAT at the arena.