Ha, I love that this board has created at least two new Chuck fans due to the Yvonne/Carol talk. It warms the heart. Glad you've enjoyed it so much Mike. I've been re-watching it a lot recently too. I think it's safe to say that's becoming my go-to feel-good show.
And while I absolutely do NOT subscribe to the notion that because Sarah and Carol have a lot of story similarities it makes Yvonne a good choice, I do think she'd be a great choice because of what she brought to the role - warmth, gravitas, toughness, vulnerability, believability and likability - all qualities that would serve her well as Carol. I feel like her work on the show was pretty underrated because she wasn't one of "the funny ones" on it (though she certainly had her moments, especially in later seasons when they let Sarah lighten up a bit), but what becomes clear the more I watch it is that she's really the one who grounded the whole damn show. She was the one whose job it was to sell the drama of the situations, and it's because she was always so natural and believable and completely sold the stakes (whether we're talking Chuck's fate or "the world's" fate) that the whole endeavor worked. Zach Levi was great w/ the lighthearted stuff and the sweet, quiet, poignant moments, but when things got really dramatic, he tended to get a bit over-the-top, imo, and I honestly don't think he could have sold that drama on his own. Yvonne's the one who brought it home pretty much every time.
Of course none this matters because she doesn't stand the slightest chance of being considered for this role, I'm sorry to say. So my top choice remains Emily Blunt because she's just as perfect for it, amazingly talented and a FAR more realistic option. But hey, if Yvonne turned out to be some Chris Pratt-esque "who?" pick, I'd be thrilled, lol.