She's not very good at this is she? Meaning answering nosy questions. She needs some old MCU training how to avoid spoilers. Or else she is going to give the whole game away.

Killing Quicksilver is perhaps the single biggest mistake Marvel Studios has made. They've made other mistakes but they've rectified most of them over time, like Trevor Slattery playing Mandarin, for example. Joss Whedon always does this in his films, he kills characters for shock value or if he's at an impasse in his storytelling sacrifices characters to give others story. Killing Quicksilver was in service to giving Hawkeye a story in AoU. All I see is lost potential for future films due to Quicksilver's link to other properties, like Inhumans, etc.

WandaVision is a great first step in least giving Quicksilver some deserved attention. My hope is with the introduction of the multiverse that Marvel has found a way to bring the character back in Doctor Strange 2. If they can bring back an alternate 2012 Loki or time-jump a 2014 Gamora into present continuity, they can bring in a multiverse Pietro without undoing what has been presented already in the films.

Regarding a potential Pietro in WandaVision, I'm fine with Evan Peters playing the role since he most likely will be revealed to not be real or will actually be someone else. As long as the true MCU Quicksilver appears in the form of Aaron Taylor-Johnson comes later.

Pretty obvious what's going on.
Wanda found a portal to Hell in Westview, New Jersey. She decided to enter in order to find Vision. She found him, but Mephisto caught her and created this fake world for her so he could have his kids through her (Wiccan and Speed). Wanda likes this new reality and wants to keep it, even though it is evil.
The citizens of Westview inside are dead. Wanda and Vision will realize this, and try to escape in the end. Vision will turn into white vision and be "resurrected".
Wanda, Wiccan and Speed will also escape but we will know Mephisto is the father.
Not sure if Pietro will appear but it would be great if he did.