Well, damn. Looks like I was wrong. I fully predicted that Sunrise would post The Witch from Mercury on their Youtube channel as it airs, but it turns out that this is only half true. It will only air on Youtube in Asia and Oceania. Meanwhile, the rest of the world will have to pay Crunchyroll for the privilege.
I’ll fully admit I was wrong, but I’m still in shock about this news. Iron Blooded Orphans, Build Divers, and Build Divers: ReRise all showed up on Youtube (in addition to other platforms). The only “new” Gundam content that I know of to air exclusively on Cunchyroll is the TV adaptation of the Origin OVAs, which isn’t quite the same situation.