Soul is least likely to get a solo. I feel like he will take up variety content. Most likely are Theo, Jongseob, or Jiung.
For those wondering my reasons: I think Theo has a good chance of breaking into the Korean GP his vocals are good for ballads and OSTs he could even be an actor or have interview show type content, Jongseob and Jiung write and produce their own solo songs on Soundcloud already so I think it's fair to say they are at least interested in having a solo career (possibly). As for Keeho and Intak, ???? I don't even know. They're like wild cards, they'll do well with anything they do. Keeho could have a successful solo career, variety content, content creation, his own talk show, literally anything. Intak will 100% be an actor but he could also do dance mentoring, mentoring on a survival show, solo career, or even do the talk show thing with Keeho. All of P1harmony is pretty well rounded and they could all go solo but I feel like if anyone was least likely it'd be Soul. I hope he would though I feel like it'd be number 1 on my spotify wrapped for the rest of my life.
From most likely to least likely
1.) Theo
2.) Jongseob
3.) Jiung
4-5.) Keeho & Intak
6.) Soul