Hard to tell.
The past tells us a few things here:
- there are different types of players. Not all systems/worlds of lore appeal to everyone
- many people will switch only if they can keep playing their favourite armies they have invested a lot of time in
- many people have very specific preferences and will not switch if those aren't met.
- it depends who you play with
- marketing plays a huge role
- complexity (or lack thereof) can get people into the game, and will repel others.
- army sizes (number of models) plays a role
- pricing plays a role
- initial hype and hate can play a role (first impressions)
Example: Me and my buddy:
- no GW store anymore in our town, just the two of us
- all our armies are on round bases (we started with AoS).
- my buddy has a problem with complex rules, us playing AoS together usually requires me to be the "game master" and explain rules. A significantly more complex game would just not be feasible. The complexity level of the most recent 40K edition would be the maximum.
- I have Seraphon/Lizardmen, Legions of Nagash/Vampire counts and Sylvaneth/Wood Elves while my buddy has Ironjawz/Black Orcs, a few Bonesplitterz (Savage Orcs), Stormcast Eternals (no equivalent) and Nighthaunt/(were those Vampire Counts as well? I don't know).
If there is a way to play at least one of our armies each and rebasing is optional (we would use house rules and movement trays or something) it could work and I would at least buy the rule book and the army book).
In my case I would probably try and build a new army, most likely magnetizing models to use round or square bases. I would not build an army that I can only play in TOW.
- I would most likely not build a huge army. We often don't have _that_ much time to play and I don’t intend to spend 400 bucks on models and books and spend 6 months painting them (the models, not the books) if I don’t know whether I like the game.
According to GW themselves AoS creates a lot more revenue than WHFB ever did (Not nearly as much as WH40K though) and the ever-growing number of (AoS exclusive!) Stormcast models tells me that they are not interested in letting AoS die anytime soon. Quite the opposite, it seems that AoS is gaining momentum. More armies, more books, the rule set since AoS 2nd edition has drawn in many players that formerly played other systems and would not have played AoS 1.0, and the lore is getting deeper and more interesting with new novels and the like being released.
Eventually? Who knows. If TOW is significantly more successful than AoS economically AoS might die in a few years. However they will have to do a lot to make it more interesting. The short wave of nostalgia from some (certainly not all) old 6th, 7th and 8th edition players and the interest in the Old World caused by the TWW video games will only do so much. They need more.
