There's no doubt in my mind that the time keepers were a trio, one of which may have been (and still is) Kang; I'm wondering whether he got greedy though and killed the other two?
So how far into the future can the TVA jump? I was under the impression that the Timekeepers were molding the future on an ongoing basis, but the TVA jumped to (and knew about) a hurricane in 2050.
They should be able to go anywhere in time; since it's dawn, right until the collapse of the universe.
That said, it's possible their technology only allows them to travel up until a point that the timeline is managed. If these strains get out of control, then there is no definite timeline, and thus no solidified end.
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I do hope this show has more of a wrap than WandaVision did, cause that was kinda left open - although the Loki series has to be left open too, especially as Kang will be the Ant Man 3 villain and there's got to be some wild connection between the Loki series, WandaVision and Quantumania.
It seems inevitable that this Loki will one day meet Thor too, maybe not until Thor 6 or something, but it'll happen, I'm sure of it.
Edit: I do find it ... peculiar, slightly, that all of these timeline variations and such just so happen to take place on Earth too - and that the TVA appear to be human. Whilst I'm sure Disney have a budget to watch, would it hurt them to be a little more ... creative?