The lesson we can take away from XMPP, I think, is that yes corporations see federation as a big legal/compliance/spam/etc. liability, because it is, and they're only going to touch that if they see it as the only option. If they're even flirting with federation, it means we're winning. They know this is the future and they don't want to be left behind. But they will try to do everything their way, not ours.