At the moment there are hundreds of thousands of Expats working here to do all this construction work (myself included) and we need place to stay, but who's going to live in all these properties when the construction industry slows down.
Burj Dubai (under const.) currently the worlds tallest building.
We are also in the process of constructing the worlds largest traffic jam. The transport infrastucture around all these tower cities is limited to say the least. Most towers have sufficient basement parking for the occupants, but in my humble opinion, the service roads seem totally inadequate (apologies to any Dubai Transport Planners reading this). An ex-colleague of mine used to tell a story that 'Elisha Otis', the man who invented the safety elevator, was also responsible for inventing the traffic jam, as high density accomodation became a reality.
Jokingly the other day I said to colleagues that I hoped that Dubai wasn't in a seizmic zone or else we could be in for the worlds largest game of toppling domino's. What happens today... we had an earthquake. OK, the epicentre was across the Gulf in Iran about 120 km away, but we cerainly felt the tremors. Fortunately there's been no damage that I've heard of, but it does make one think.