Originally Posted by
Caerule
I finished reading the book myself now.
For me, it clarifies things nicely, and matches what I had come up with, myself.
Basically, there is only one main timeline, shaped by our actions in what qualifies as the present. Before the occurrence of "now" lie infinite possibilities, paths for every choice and possibilities, but only one of these will be the path the true timeline takes. The other options and possibilities not taken, exist as shades of possibility for a while. Bronze dragons and the like can browse and study these, but unless the folks from the true timeline start messing with them, they fade away like shadows.
In that way, the infinite timelines existing simultaneously, or in the past of the path of the true timeline are but fading echoes of possibilities not taken. They are like trees that fall in a forest, when no one is there to hear the sound. If there is no there to hear the sound, the sound fades away without impact on anyone or anything.
This explains well the state of the timeline Thrall found himself in when he was searching for Nozdormu in the Twilight of the Aspects book. The timeline he was in was different from ours. Things happened that shouldn't have. And so as time stretched on, it became less and less real, and time was developing flaws. Thrall from the main timeline made this timeline "real" for a while, but it was already degraded. And when he focused himself on living in the moment, in the actual "now", it faded away quickly again, to the mere abstract of possibility.
Alternate Draenor is definitely one of those untaken branches of the main timeline. Meaning it was merely one of the infinite possibilities, that became manifest with the arrival of Garrosh and Kairozdormu, altered by them and sustained by its connection with the main timeline through the shard of the Vision of Time artifact brought to it.
That shard was apparently removed again after WoD, according to the latest datamining dialogue, as the connection has to be restored to get to Draenor.
What breaking from the main timeline again will mean for the fate of Draenor is unclear. We impacted that timeline a lot, and carry experiences from it with us. So I'm guessing its existence should remain stable for a good time at least. But I am no Bronze Dragon. If I was a Draenor Orc though, I'd prefer that connection wasn't closed again...
Either way, as long as you don't go messing around with the actual past of the actual timeline, it would seem you're in the clear where it comes to catastrophic consequences to time itself.