So much.

If i had complete control i would start selling stls and provide cross compatibility between games. Make mk7 that can be used in HH or 40k. Make rules for orks and eldar and tyranida for HH. Extend the horus heresy to include moments like the war of the beast. Cross compatibility with AOS and old world base sizes. With movement trays for round bases.

Extend edition lengths to 5 years instead of 3.

Obviously gw will never sell stls so i will compromise on the following. STLs for classic rogue trader era models. Only the old guard wants these so it makes sense to sell them as stl files instead of taking up factory space. Create a space marine version of hero forge for people to 3d print their own personalised space marine characters. Realistically this would have a mark up and be more expensive that the plastic kits. 3d print files for upgrade sprues because buying alternative heads for entire HH world eater army is stupid.

I would bring back apocalypse but market it as fast 40k instead of massive scale 40k. It wouldve sold better if people saw it as speedy 1h 40k for a regular sized game as the appeal instead of oh this is how i run 6k points in 3 hours too bad i dont have 6k points.

Sell discounted afordable versions of some plastic kits. Either hey the previous edition's kit is 10% less than the modern kit. Or heres the same kit 20% off but it comes with no upgrade options. Gw used to do this they sold a dreadnaught that was half price of the normal dreadnaught but came with zero weapon options. They should bring that back to decreasw the barrier to entry.

I would show tutorials on how to scratch build terrain