As part of a 40K RPG revival, and to suppliment my vision of the 40K universe I have almost completed the "Twenty". Yes 2nd Legion and 11th Legion live on, as do their Primarchs. Lots of cloak and dagger, destruction of the Imperium, Chaos rampant - but not the end of worlds (like Age of Sigmar). Will in due course post more narrative as I develop it.
I've been looting my old Rogue Trader marines to build up this eclectic force of heroes and rogues. Still sourcing something suitable for the 2 Primarchs, but they won't be giants, perhaps a head taller than a standard marine.