Scarlet Witch could permanently restore Vision in stolen Vision's body from a SWORD facility and created a strange, twisted reality in which he has been restored to life.
The idea is lifted straight from the comics, where Scarlet Witch has long possessed the power to manipulate reality itself. The problem with such abilities is that they come at a terrible cost; it's almost uniformly the case that reality manipulators suffer from severe psychological problems. "Can you understand the delicate mindset of a woman, a person, who has control over reality," Doctor Strange asked Wanda's friends in Avengers #503. "It means reality controls her. Imagination becomes the enemy. Structure disappears." Viewed through that lens, the sitcom format is an attempt to impose structure, one that is failing because even Scarlet Witch can't perfectly control reality itself.
The most intriguing question, of course, is whether or not Vision will be permanently restored to life at the end of WandaVision - that is to say, whether Wanda's mysterious powers could rewrite reality permanently.
Vision Seems To Be A Real Being
There's been intense discussion over whether or not Vision has truly been resurrected. The first few episodes of WandaVision had seemed to imply he existed as a product of Wanda's own imagination, and at times his questioning her seemed to be a manifestation of Wanda's subconscious recognizing flaws in the nature of the Westview reality. But by WandaVision episode 5, it's become clear Vision possesses a strong sense of autonomy and independence, and he enjoys a degree of freedom not experienced by the other residents of Westview. They must bend to Wanda's will, but Vision is allowed his own personhood. Thus it looks as though Vision has actually been brought back.
It's reasonable to assume Scarlet Witch used her reality-warping powers to reassemble Vision's broken body. One flash in WandaVision episode 4 suggested there is actually a gap where the Captain America: Civil War, he had developed enough understanding of his own psyche to consider a foreign consciousness, something on the borders of his mind rather than an integral part of it. And so, with his body and circuitry repaired, Vision could really have been resurrected.
Scarlet Witch Should Pay A Price For Restoring Vision
Death has always been something of a revolving door in the MCU, a trait inherited from the comics themselves. But if Vision has indeed been brought back from the dead, the first full resurrection, then there must be a cost; anything else would be dissatisfying in narrative . It is possible the first hints of that cost have already been dropped, with the increasing acrimony between Scarlet Witch and Vision potentially setting up their breakup. It could well be that Wanda has succeeded in resurrecting Vision - only to lose him forever because of her actions.
But another possibility, taken from the comics themselves, is that Wanda could be forced to create a new life for herself. WandaVision is strongly influenced by a 2005 comic book event called House of M, and in the aftermath of that story, Wanda simply disappeared. Her fate was apparently revealed in New Avengers #26, with Doctor Strange explaining she had written her own powers out of existence itself. "I'm a trained sorcerer, and yes, I can track all the magics all over the world and find those who are using or abusing them," he explained. "And, in the past, to find her, I have. All I know is she's not using them anymore, so I cannot find her." Hawkeye eventually succeeded where Doctor Strange had failed, discovering Wanda living at the foot of Mount Wundagore in Transia, the place of her birth. She had essentially reincarnated herself into a new life, one where the tragedies of the past had been forgotten and she enjoyed a fresh start. (Granted, this was all retconned, but for now let's ignore that.)
Scarlet Witch Could Introduce Mutants Into The MCU
As Stephen Strange learned in Doctor Strange, reality is a fragile thing. There are already signs Wanda's manipulation of reality is affecting the Multiverse itself, with Fox's version of Quicksilver unexpectedly appearing in WandaVision episode 5. If Wanda did indeed attempt to do this - if she allowed Vision to live independently, and tried to give herself a fresh start - that doesn't necessarily mean she would be rendered powerless. It is more likely that she would make herself something... different.
In the comics, Scarlet Witch's reality manipulations built to a climax in which the entire mutant race was brought to the brink of extinction; she depowered all but a couple of hundred mutants, deactivating their X-genes semi-permanently. There would be a certain degree of poetic irony to Marvel choosing to invert this story in the MCU, with Doctor Strange in the Multiverse of Madness - confirmed to follow on from WandaVision, and also featuring Scarlet Witch - as one of the most exciting films in the MCU to date. Doctor Strange would need to deal with the changes to reality caused by Wanda Maximoff's flare of power, discovering she has created an entire new class of powerful superhumans.
But it is important to understand this fresh start would be no Happily Ever After for Wanda. In essentially retconning herself, creating herself anew, she would have sacrificed everything she was and ever had been - all the friendships and relationships, all the joy as well as all the trauma. Even though she had achieved her goal of resurrecting Vision, she would have achieved this by turning herself into a person who never knew him - and who was shaped by events into a completely different person. That would certainly be a tragic twist for the Scarlet Witch at the heart of WandaVision.