Ohtani will pick one or the other in the next couple years, I guarantee it.
If he hits well (like all-star type numbers) he will quit pitching, if he doesn't I think he will become a full time pitcher.
simple reason is increased odds of injury, do you want your star pitching playing 2-3 days when he is not pitching and potentially getting hurt? or your star fielder/hitter pitching just because they are pretty good but that gives them a huge odds increase for injury as well.
and technically, what is 2-way? because maybe I am wrong but aren't the Angels just using him as DH, is that really 2-way? in OOTP they actually have the guys playing in the field. In my mind a true 2 way player would have to play in the field as well.

(I know he can play OF, but Angels are obviously thinking injury risk as well). So WS game in NL park, would he play in the field or just pinch hit?