I wouldn't say that all "raised expectations" were "all in our heads." She may not have aggressively set them, but she didn't dissuade them, either.
She was active in endorsing candidates all over the country, which suggested that she still wanted to play a role. It also suggested that she was laying down a base in Congress to leverage later. She was active on social media offering frequent commentary on politics. She wrote her book, Going Rogue, which she ended with "Sarah's not retreating, she's reloading."
When Palin bought a house in Arizona, sure, many thought she might be moving there to run for retiring Jon Kyl's seat (with McCain's endorsement). Others thought she bought the house to be close to her daughter who moved there. When McCain turned on her in the end, it put to rest the former supposition. Bristol Palin sold her home in 2012 to move back to Alaska, and Sarah sold her home in 2016. McCain didn't make his "regrets" comment until 2018, but his people were floating negative stories for years before.
It's possible that the McCain camp told her that if she ran for office he would oppose her. It's possible she stopped her plans when the children's problems became too severe. It's possible it was all in our heads and she wasn't planning anything.
It's possible that she retreated, not reloaded, after all.
From what I was reading at the time, I doubted that she would run from Arizona, because McCaine and his group were against her from the time she was picked as his running mate. I don't think that they really knew her, nor understood her; let alone just HOW much people would favor her and yet, still hate him! That stuck in his craw and then there was that B*TCH on wheels...Nicole Wallace, who already had a BAD rep when he picked her to use for "helping" Sarah.
The harassment, abuse, and vilification of Sarah and her entire family, sadly has NEVER stopped! So I imagine that running for anything, today, would be not just difficult, but IMPOSSIBLE to win and then there is the fact that she has an 11 year old with Downs. He will reach puberty soon and that is a difficult time for normal kids to go through and often worse for a Downs kid. She's needed at home!