The temporary accommodation is at the Marina because Emirates have serviced apartments there that are not yet full. Hence, it costs very little to put people in there, although it is a very, very nice tower.
There is not a snowball in the sand's chance of permanent accommodation being at the Marina- it is just too expensive.
If they offer you permanent accommodation and you don't like it you always have a choice- you can take the utilities allowance instead. If you don't want to do that either then I have a strong feeling you will be in temporary accommodation for a long, long time as every time you turn down an offering you will go to the bottom of the list again.
Don't be under any illusions that you have any control over where you will end up living in Dubai if you are in company accommodation. It is a chance you take when you join.
