I really enjoyed this episode and what a series this has been!
I have to say, although there are so many hints at Kang (the TVA, Ravonna, Alioth, timelines etc) I can't help but think he won't be the villain, as much as I'd love him to be. I can't wait for him to appear at some point.
It just doesn't fit the narrative or theme of the series. I try to put myself in the shoes of the writers and look at it from their perspective. They have to tell a story which works not just for us fanatics but also the general audience who won't necessarily know who Kang is.
To introduce a random villain in the final episode just doesn't fit narratively or thematically and that's why I don't think it will be Kang. If anything I think Kang may appear in a post credits scene tease, perhaps he was lurking in the background, perhaps this even sets up his origin story? But I don't think he will be the villain.
For me, I think the villain has been staring us in the face from the beginning. It is Loki. Or rather, a Loki variant but one who won and is subsequently completely evil. Perhaps he was brought in but defeated the Timekeepers and replaced them with robots, taking control of the TVA? Some of the deception around the TVA is classic Loki after all.
They could really go the Doctor Who paradoxical route and make it a form of time loop, where our Loki that we are watching reaches this castle and realizes he is the one who sets up the TVA in the first place, creating the events of the series and a causal loop.
Either of those things to me fit more with the narrative and theme of the series, about destiny and identity.
Interested to know others thoughts on this, hope I made my theory clear enough and didn't waffle too much. Love this series!
ps. I just noticed there is a finale speculation thread so I'll post this there too.