answering in general, also run out of likes.
I strongly doubt Astrid is a few millenniums old. Centuries? totally, but there is no way she is from the time of ancient Greek. If that was the case, her control over the archon would be almost absolute. While age not only makes you more powerful, it increases the likelihood of being of lower gen.
So Astrid from ancient Greek would be say 7th gen with a 2000 years? and she is not able to truly control the archon?
My guess is that Astrid is around 500-1000, even potentially younger. From the visions MC had, Sharon was very close to her and I doubt Sharon personality changed much. This open to two possibilities: either Astrid was once a cute little vamp whose values were close to Sharon (like not pure evil abla bla bla) or Astrid was hiding her true nature.
One way or the other, it does not fit for me that Astrid is an overpowerful vamp. I'd say 8-9 gen and around 500-1000 at most.
And I doubt she knows what MC is. I think there are two things at hand for her desire for MC (unfortunately, none are because she wants his dick

). First, simply to hurt Sharon. Second, she most likely subconsciously feels MC's power. So for some reason she feels the need to keep him for her, probably thinking she is doing it to hurt Sharon. But there is no way she knows exactly what MC is neither she is so ridiculously powerful. If that was the case, why the need to make something so complex as using the hunters? Just go and retrieve MC by pure power.
I strongly doubt Astrid will die soon. I do believe, she will keep playing an important role, but she is at most a second degree villain here. In fact, I still support the idea she may be one of those characters whose allegiance is simply her own and might do what she needs now and then, for or against MC. So she will play an ally in the future and potentially betraying us. Things like that.
Thing is, they have spent quite an important asset creating her. Not only her model is absolutely gorgeous, too gorgeous to use it to kill her so soon, but they also invest in some "clothing" for her. If they simply wanted a character to kill so soon, they could have use a simpler, more common design. Yet, they went with this total babe and even get to make her showcase how good all the costumes fit her? nahh.. she is here to stay.