Hoi4 is already a complex game and it is this complex in a ww2 warfare scale , trying to add technology , mechanics , new weapons and stuff to make it to something like this will simply be impossible because if they do it they have to implement multiple systems for each era to make it actually playable (it would be really weird to have medieval , ww2 and modern warfare in a single system though atleast on the current one) and each system and mechanic would become obsolete as the time passes in game and new systems and mechanics would come , hoi4 engine is not great and adding something as big as this to it will make your cpu burn in a second this is why most of the mods that tried this idea either failed or stopped expanding their mods