On another note,
I don't even think the card game is necessarily proof even if the Norns weren't retconned.
It doesn't say the Yggdrasil contains an infinite number of potential timelines, it says the Well of Fate allows the Norns to see an endless number of possibilities, and they can play out many timelines of events. This is a very important distinction.
First off, timeline doesn't necessarily mean alternate reality, it can also just mean order of events.
Secondly, in order for there to be something like
2-A, it'd have to be confirmed that each endless possibility generates a (confirmed) timeline unto itself rather than just being something that can be seen.
Lastly, this is a bit of an expansion on the previous point, but since all they say is that possibilities and not timelines (again, assuming they're even actual alternate timelines) themselves are endless, we don't really know the mechanics of this. For all we know, it could be like Dragon Ball where timelines aren't generated naturally, but through intervention.