This is it.
This is the moment beyond which we cannot return. For both the Alliance and those members of the Horde in open revolt, there is now no longer any path but forward, and that path leads through Orgrimmar's iron walls, past her legions of defenders, and must inevitably lead all to the iron throne of Garrosh Hellscream in his subterranean fortress below Orgrimmar itself. The Warchief has declared his intent to lure the armies of the world to make open war against him on his terms, on ground he controls, and within a week that intent will have become reality. The die has been cast.
For some, this is the culmination of a desired confrontation. Both Vol'jin and Jaina Proudmoore fall into this category - both want the Warchief removed and some measure of revenge for personal slights and injuries. Vol'jin's grudge is of longer standing, and his desire for retribution stems from an attempt to have him assassinated, but Jaina seeks redress of a loss of an entire city in the bombing of Theramore, the loss of an apprentice, of friends and colleagues and the last refuge of a refugee people. For others, like Thrall and Varok Saurfang, this is a conflict of brother against brother and they seek to avoid it even as they suspect that it cannot be avoided. Still others, like Lor'themar Theron and Varian Wrynn, were brought to this point reluctantly and only act now in the best interests of their people.
Some reluctant, others eager, but in the end it all comes down to this - two full scale armies invading the most fortified, heaviest defended place on the planet Azeroth. The war that Hellscream began has finally found its way back to Orgrimmar.