That isn't an "according to his sources," they have all been announced by Dubai. Disney is the only one not building there, and Dubai is doing that intentionally. They are trying to BEAT Disney... not BE Disney.
As far the shortage goes... I believe it. The outsourcing problems that have been developing within WDI are evident (Stitch's Great Escape... hello), but Disney hasn't needed a large group of imagineers since the late nineties for Animal Kingdom. But they do now.
An imagineering lay-off during the development of AK led to them jumping to Universal for Islands of Adventure. The same thing would happen with Dubai because, for non-Disney fans, it's huge. Dubai will become our Tokyo Disney (the land where money is no object).