The Alliance could do ANYTHING to the Horde and it WOULD be justified.
Because the Horde has proven TIME AND TIME again they are unable to resist the urge to launch unprovoked wars with the end goal being genocide.
The Horde has proven TIME and TIME again they are unable to keep there own house in order, and CONSTANTLY need the Alliance to show up and bail them out of the sh*t smeared mattress they lay in.
Seriously its literally only the Alliances MERCY that the Horde still exists, and that is a mistake if you ask me.
The Orcs should be forcibly relocated back to Outland en masse.
The Tauren isolated in there home lands, and the trolls all relocated to the Zandalari isles.
The Goblins that have sided with the Horde that entire Cartel should be slaughtered.
Nightborn herded back to Suramar,
Blood Elves Isolated in Quel’Thalas,
Vulpera should join the Trolls and be cast back into Vuldun.
The High Mountain Driven back to High mountain.
The Forsaken should simply be purged all together, to finally remove the blight of Undeath from the Northern Eastern Kingdoms.
This is what SHOULD happen, as the Horde has simply proven itself to be nothing more than a genocidal war machine with a thirst for the blood of innocent in lore.