We don't know. It's very possible, however. What do you think about it?

I think Agatha Harkness will appear as a reoccurring villain/supporting character throughout Scarlet Witch's appearances. Wanda could return to Westview to get information from Harkness about the villain of Doctor Strange in the Multiverse of Madness or if she is the villain Doctor Strange can do it to understand what she did during WandaVision. I think the "Scarlet Witch" is going to be turned into a scary story that parents tell their children about within Westview "do you're homework or the Scarlet Witch will come for you" and those who experienced the events of WandaVision will know about Agnes actually being a witch who Wanda returns to during important moments in her character arc

Almost definitely. Marvel tends to set up "clues" in their writing, and they set up several in the final episode of WandaVision. Agatha points out that Wanda will need her. Wanda says she'll be able to find her.

Not to mention Agatha is a fan favourite and they've kept her alive, and that's usually enough to bring them back.