Not Libel, but satire and the article clearly indicates that the quotes are satire.
No, I doubt that it’s winnable as libel. Sarah is/was a politician, and a public figure, and they are fair game.
Sure, she hasn’t declared yet, but I doubt whether a court would think that mattered. She is still clearly involved in presidential politics at the present time, as a possible candidate and as someone who is involved in political disputes leading up to various elections.