There has been a lot of discussion about it in the past, but right now it's unlikely to happen. It would add one more complex thing that you would need to manage and there wouldn't be much upside (remember, any team can sign any player from any other team's practice squad to their active roster, so essentially it's no different than pulling someone out of the FA market). The only benefit might be that they would learn your playbook, but I haven't felt that is a compelling reason enough to add the complexity.
