I think its more than potential to be dropped. The union report that there will be no permanent contracts taken on in 2009.
As the 12k on the cadet salary is tax free it works out slightly better than the DEP salary (as gyni says) so hopefully when you return you will come back on the cadet salary. It would be rather rude if they brought you back under TRSS!!!!!
The problem is I am not sure if EZY see the £1000 a month as paying for the TR. You are being paid by CTC while finishing the training. Although my argument would be that the course includes the TR and line training and therefore you shouldn't have to pay for it again and should join as a DEP. This then poses the question of whether you join the DEP hold pool and wait as TRSS guys sneak in first or if you get special treatment as you were only layed off for 6 months and come back on the cadet salary???? If things really don't pick up you might find yourself back for another 6 months stint on a Flexi contract anyway!!!
Lots of unanswered questions. Those of us in the union need to keep poking to try and look after you all but it sounds like they will be unable to do anything unless it presents a flight safety risk.
I don't think anyone will be able to give you acurate advice as there are so many variables. If you're not in already, join Balpa, and speak to the company council after "joining" EZY. Whilst being unable to represent you directly at least they can give you the best info as what to expect.
Sure you are already but just plan for the worst case and anything else will be a bonus. Good luck.