I do hope Age of Sigmar gets reversed, however seeing that some people do like it, and GW already spent 90% of their budget for the next 20 years on a ridiculous statue in their front lawn the chances are low. I personally would do it like this:
- Restore the good old Warhamer lore continuum, not end times stuff.
- Develop/revive specialist games for it. Specially Man-o-War.
- Lower Prices.
- Do a crazy promotion of everything (magazines, novels, codices, from all editions) in HD digital quality form, for a few bucks for a week or something to get some hype, and then leave everything in the online store forever at reach to anyone willing to buy it.
- Get a quality assurance team that manages everything going out, so everything new fits into the lore and continuity (previously discussed and stated).
- Leave Age of Sigmar not as the result of the universe blowing up, but rather being the afterlife itself. A realm past the chaos one, where Sigmar is fighting the forces of Chaos to cross over back to the terrestrial/physical/real plane where the Warhammer Planet is, and fulfill it's prophesy of coming back for the end of times (of chaos time that's it).
- Total Warhammer was a good start. Next time find a developer (or force CA) to actually make the whole world map, add in naval battles and put in even more/better strategies/mechanics to the game.
- Try to do bundles of real life merchandise with video games. Kind of like those Disney universe (or whatever) games.
EDIT: Also:
Find Matt Ward. Get Goto. Put them on the same room. Make them fight each other to death using only their fist and poorly written novels/codices. Kill the survivor dropping a crate full of his poorly made books.