Don’t hold your breath. The introduction of the Agency window was fueled by discouraging cooperation with other players and to hamper participating in PVE activities in general. Re-introducing features that actively help people to work together in PVE is going against this plan.
By forming a fleet as before and then he has to warp to you after you landed on the mission beacon. Sharing the journal like before is not possible as far as I can see. I can only drag agents not mission information.