@snochick_18 6.0. There will be a few weeks of 20-player Mythic SoO (along with flexible N/H) before Draenor unlocks.- Watcher (@WatcherDev) March 25, 2014
What this means is that we'll get a completely redesigned SoO with the class changes and other new systems in mind, but that older raids won't be changed, since they're considered trivial in comparison thanks to gear. It also means we know the 6.0 patch will be relatively shortly followed by Warlords of Draenor, and not well in advance of it, as some have speculated. So if you're wondering how your guild will fare with the change, patch 6.0 will be your test drive.