Gebre has too much reactive feet for running cross country. For using in the best way his attitude, Gebre needs a very hard ground, not soft and not flat like cross country courses. On the contrary, Bekele is very strong in his thighs, and uses his feet in different way.
Sihine (like Gebremariam) is taller than Kenenisa, and a high height is not favourable for running cross. In Bruxelles, probably, the course could be very muddy : in this case, nothing to do against Bekele, no match with Sihine and the Kenyans.
In any case, forget Tergat : he will not run World Championships. I'm sure that his focus is London Marathon, so WCCCh are not possible in top shape (and, if he's not in top shape, of course has no reason to compete).
Instead, short race can be very interesting, because is my intention to put Shaheen in the race. He never ran a cross, expecially with mud, and never will run before WCCCh (the only race could be World Military Cross Ch. in Lebanon on 7th of March, but on a very dry course), so may be that his attitude for cross is not very high ; but, having a wonderful talent, I'm curious to discover his possibilities in this new event.