What if Garrosh escaping to an alternate Draenor, was not an alternate timeline at all, what if a Singularity was created instead, and what we are seeing is the Singularity collapsing upon itself with the Garrison as the primary focal point. As the expansion continues more and more of the denizens of this alternate universe either move in towards the Garrison or cease to exist. Soon all of the World bosses will be there, soon we will not have to worry about travel to other areas, it will all collapse onto the Garrison. We will become the focal point of the Singularity until we reach a point where it collapses upon itself.
When it was created by Garrosh his desire and will shaped everything, in killing him Thrall has started to unravel the framework that held it all together. At some point we will have to escape or be forever lost.
All of this is shear speculation and not based on any lore or scientific fact, and strictly for amusement purposes only.