Rappers gonna rap.
In all seriousness, I doubt that would be implemented. And if that happens, well, the user on a "BRB" is responsible for where they leave their character, this is the same for the way things are now. And how they leave their character. I'm not going to AFK with my character on its back, that's just ASKING for trolling. If you afk sitting, how's that gonna work? It won't. Problem solved via the player's own actions.