In that 16 years she was a two-term Senator and Secretary of State. I don't think Michelle would be able to match that in 3.5 years (since 2019 is when the primary season starts).
True. A better example would actually be Bill's second-term ending in 2000, and Hillary becoming Senator in 2001. Prior to that, though she campaigned as her own person on women's and children's rights, she didn't actually do much in actual politics?