Genuinely curious: Why would she get another CEO job (excluding startups and sinking ships)? There was no reason to think she would do a good job at Yahoo, she has no track record of success as a CEO, she certainly can't point to anything she's done at Yahoo, and as far as I can tell, people don't like working for her.
Many CEOs have negligible impact.
Judging her on her track record would just be sexist.
Seriously, it doesn't make sense. You can pick other people, who haven't been CEOs yet, but have shown potential. She never showed potential. Quite the contrary I'd say.
Once you're in the inner circle, unless you messed up MAJORLY (i.e. bankrupted a billion dollar company), you'll always be able to get a new gig at some point.
Yes, it's not always a meritocracy - yes, that's how the world works. If I sit on a board, would I rather appoint my buddy, who will have my back? Of course.
As much as I think Marissa did a terrible job, she didn't pick the easiest company to become CEO of. Some CEOs have it easier than other; certain companies run on autopilot and have just a few major competitors.
Under your context, which is indeed the reality, both my comment and my parent's comment are irrelevant.
There aren't enough high profile companies for Mrs Mayers to expend until she acquires those skills, which we know she doesn't have. If for some reason she acquires them in the future, good for her. I wouldn't invest on that hope though, and you have no argument to convince anyone that they should.
She seems absolutely obsessed with the fashion industry (why did Yahoo need to open an office in Milan and spend $3 million sponsoring the Met Fashion Gala) so perhaps some sort of online fashion store would be a good fit, like Net-A-Porter, Shop Bob or Poylvore.