Anyone else think Allison Mack might make a good Federation caption? In the style of Ezri Dax. And, assuming that de Boer isn't available, or has aged more than Ezri in the interim. (She's 40, and Ezri isn't.)
I know she played as a high school kid in much of Smallville, but recently she's dropped the adolescent voice and attitude and begun acting as an adult.
I think Nikki De Boer has aged well. She was 29 years old playing Ezri in Season 7. Ten years have passed in her life, five have passed in the novels. At 40 she looks great and could easily play a character who is in her early 30s.
A Starfleet Captain has to look more grown-up than she did in Season 7, so the aging is a good thing, IMO.
Allison Mack still looks too young to be a convincing Starfleet Captain, I think.