It is very normal that any new management trying to implement new policies serving their goals and ideas.
On the other hand we should always have alternative plans.
Short term plan: which some have mentioned resign the 320 training and fly as a "330 or 777 line captain" and forget the instructor position (it doesn't worth any way, especially on the 320).
The 330 instructors may apply for the 777 transfer.
Long term plane: shop around for another airline/country.
I think the 320 instructors should wait few weeks & see if this "promised" MFF (mixed fleet flying) is going to start at all or not? then you may decide.
If they start the 320 to 330 CCQ soon, it is better for the junior instructors, if not then you know you are stuck for long years on 320 doing the hard work (double rotation...etc) while the 330 SFEs are using your sim slots, in other words you will be line instructors with TRE salary!