I never heard anything about such a link road. In fact the road condition in Emaar is so bad that it is unthinkable that they can build any other road.
What I know is that the residents have been complaining about the single entry/exit point since whenever the main Islamabad expressway is blocked (that happens often) residents can't enter or exist from Emaar and this could easily escalate into something serious/emergency as the traffic congestion lasts for hours. A few months back it was almost a night long. The residents want to connect Emaar with DHA 5 so that if expressway exist outside Emaar is clogged then they can then get into DHA5 and see if that could give them an alternate route. But, again this is also not clear if this will ever be done.