Patch 5.1 tells us a very interesting story. On the one side, we have a war going on in Pandaria. This is the part we all see. On the other side, we have the unseen side - what's going on in the Old World. Currently we can't know what's going on there - the Old World is frozen in its own Cataclysm timeline - while Silvermoon is frozen in time even before the Lich King timeline. But something is definitely going on - something we don't see, but something we're going to see. Sometimes, quests take us to places in the Old world like Darnassus or the Echo isles, but those quests show a very little part of the current geopolitical situation in Azeroth
Operation "Shieldwall" tells us a story about the clashes between King Varian Wrynn and Jaina Proudmoore. They disagree about how they should handle situation with the blood elves and their betrayal in Dalaran. Jaina thinks that "Once Horde is always Horde" and they should be purged. Surprisingly, Vereesa Windruner thinks in approximately the same way - she always wanted them to be gone from Dalaran and she tells the adventurer (the player) to handle the situation as he wishes - she won't care even if he kills blood elves. Judging from her behaviour, she most probably doesn't consider the blood elves to be her relatives.
So we have the blood elves purged from Dalaran. Fine. The Kirin Tor and Dalaran now belong to the Alliance and both Jaina and Vereesa agree on that point. Fine.
However, King Varian makes a very strong point - he wanted the blood elves to rejoin the Alliance. While we (I mean, the Alliance) got Dalaran back, this was achieved through war - through purging the blood elves by force. How could we even think that the blood elves will leave the Horde after that and rejoin Alliance? This would be impossible. The blood elves won't like the Alliance as allies... not after this. Perhaps, they will serve as a temporary ally against Garrosh - just like orcs and night elves fought together against the Burning Legion. But nothing more.
Blood elves now distrust Garrosh, too. Garrosh politics lead to casualities amongst the blood elves and Lor'themar is now reconsidering his stay within the Horde.
So... as we can see, the blood elves are following a very thin line and they're about to fall in a situation where they will be with no allies. They won't be willing to ally with the orcs, and looks like they won't be willing to ally with the humans. They won't be a firm part either of the Horde, or of the Alliance.
But they still have a very strong ally, that's surprisingly absent in patch 5.1, in the current development of the storyline. In Pandaria we see Vol'jin. We see Lor'themar.
But we don't see Sylvanas. She and her Forsaken are the missing link in the storyline. And the Blood Elves depend on the Forsaken to protect the borders. Without the Forsaken, Silvermoon will fall... This is a very firm Alliance.
Which brings us to the Unseen Story. The war is going on in Pandaria and we see both the King, the Warchief, the humans, the orcs in the center. But we're not seeing what's Sylvannas cooking in the Undercity. We don't see how the war is developing in Lordaeron. The Argent Crusade is entirely absent from Mists of Pandaria. Tirion Fordring stays in his own little town... And it's doubtful he has no opinion about what's going on with the war between the Alliance and Horde.
This brings us even further to the development of the storyline post-Mists. We know that Turalyon and Alleria are returning in the next expansion. And the plot in Mists of Pandaria which concerns the blood elves leads to very interesting twists that are going to define both the blood elves and Alleria as a character.