I want to start by quoting something Fenway said:
" don't give up on hitting if you can do it"
I think that speaks volumes.
As far as the whole idea of a PO and where they fit according to the original posters topic / question , A lot of that depends on talent. Not just your sons talent. The talent he surrounds himself with in HS and travel ball.
My son is a OF/LHP two-way guy at a Division 1 school in the South. He was recruited as a pitcher. In HS he was a starting pitcher and he played OF on the days he didn't throw. For travel ball he was a PO LHP out of the pen only. 2014 thru 2016 he played on one of the top travel teams in the country ( Ranked #3 by PG ) . I'm not sure if he ever saw an AB...he did get a few starts but his role was to come outta the pen and empty the tank for an inning . That's it. That is what I mean by my earlier reference to 'talent' . The travel team he played on had 5 players in his class draft and approx 14-15 D1 commits. For big tourneys they would import starters from all over the country . Big RHPs sitting 93-95 and Big LHPs touching 93 . His job was defined by the talent level of the team. In HS he was a starter and led the league in RBI's but on a stacked uber travel team....PO outta the pen
Once again , I like what Fenway said. Midway thru my sons senior year in HS he experienced shoulder discomfort . He shut it down on the mound. But he continued to hit and did very, very well.
2 weeks before 2016 draft his high school coach received a call from a supervisor at MLB scouting bureau asking for permission to come watch BP and for my sons cell number. The scout worked out my son and 3 NCAA guys at a local college a few days later......as a HITTER .
Son continued to experience shoulder pain as a freshman pitcher in College . During fall ball he DH'd and left an impression on the coaching staff that he could indeed hit. In November last year he had surgery. Redshirted and missed all of last year. He is currently finishing up a long and grueling post surgery rehab. Playing summer ball as a no throw DH and will be cleared to throw from the outfield in games in 3 weeks. He'll return to school for his redshirt freshman year as an OF/ LHP as opposed to a LHP/OF. He'll throw off a mound again but not until after Jan 2018. In the meantime he will try to contribute as a hitter .
My point here with this long summery is basically what Fenway said " Don't give up on the hitting if you can do it". All kinds of things happen. Injuries, etc. If a guy can hit he can give himself more opportunities to continue playing and stay on the field. Pitching is great....but pitchers are susceptible to debilitating arm injuries. Injuries that require surgery and can ultimately end a career.
Keep 'swinging it'......you never know how things are gonna play out