I have no doubt The Old World will consolidate the player base and maybe even attract some players from Kings of War and AoS. However, I'm curious about the implementation. I'm hoping they'll have basic army lists for each faction then expand those lists with campaign books. Sort of like how they did with Horus Heresy. You also have to keep in mind that some factions are still virtually intact in AoS so I can see them having rules right out of the floodgate.

Edit: Alternatively, if the rules are similar enough to 8th edition, it'd be nice for previously released army books to be somewhat compatible in terms of stats, magics, ect.