Out of all the characters Pharah is the best to take over as strike commander. The narrative is even pushing for it. She has the motive, the connections, a legacy to carry on, and the skills.
1) She’s the head of security for Helix which was holding Doomfist. She’ll be pushed into action by the company sooner or later. To take down Akande she will be forced to take on Talon as well. Meaning that she will likely have to fight Reaper, Widowmaker, and Sombra as well.
2) Widowmaker shot her mother and Ana was presumed dead for about 7 years. So Fareeha is going to have a major grudge. That’s going to get personal.
3) She knew Reaper. He was, presumably, like an uncle to her or family of some sort. It’s going to hit her hard when she finds out that not only did Gabe break Akande out, but that he’s been experimented on and used by/working with Talon.
4) She will want to make her mother proud. Ana was one of the founding members of overwatch and later became the second in command. Also, Fareeha grew up in Overwatch and, likely, has fond memories of growing up on base. This brings us to point 5.
5) We are constantly reminded that Fareeha wanted to be part of Overwatch when she was a child. Being an agent of Overwatch used to be her dream. If given the chance, of course she would jump to join.
6) She is the security chief of Helix and part of the Raptora squad, a state of the art mecha suit division. She was also part of the Egyptian army and she has a commendation of ‘distinguished service’.
The only Talon character she isn’t connected with is Sombra other than Sombra doing research on her. I’m still waiting to see how that pans out because if Blizzard really wanted to push this they would give us a more concrete connection between the two.
None of the other characters we can assume join the new Overwatch have quite the narrative background suiting them to be the strike commander. Hell, if anyone should be the poster child for Overwatch it should be Fareeha.