So basically, they're telling the guys they know they will need if they're in. And for the rest they're holding off getting your hopes up before necessary, in case they don't need you...?
And the problem is....?
Trust me you do not want to be in the position of those CC a couple years back who had already resigned, sold houses, cars etc and then to be told, oops sorry we don't actually need you...
In the current situation it may be better that they are not getting in touch right away, as frustrating as it can be.
And as the others say, get used to the 'Dubai Run-Around'- it's part of life here. Either you let it get to you, or you go home and have a nice glass of grape and learn to deal, like I did today. Apparently being 'on-time' is only important for those of us working on the aircraft/at the airport.... not half of the office...