Blizzard has made it clear that they have carried story themes and narratives across multiple xpacs. It’s possible that it will come up in Shadowlands, or even later depending on how SL unfolds. As a side note, I’d enjoy it if there is another xmog somewhere for remaining loyal as I did this on an alt.
Blizzard has also made it clear that sometimes a story just gets dropped whether finished or not. It’s possible that this part is over and remaining loyal gets you nothing other than a cutscene that everyone gets to watch.
She leaves stating that in time we would understand her meaning. Maybe there will be something extra, maybe not. Just going to have to see if something happens in SL.