Casado won't make it here if he doesn't change positions. Way too limited physically without enough talent and football iq to comprnsate for it.
His best hope is the inverted Fullback that Marquez tried him at. Both him and Moha looked decent in it.
Pau Prim is a decent talent, average physically but not limited. As most Barca talents he struggles against superior athletes but it is a bit normal. It depends on his learning curve.
Bernal is a big guy, fairly athletic and talented, but he was an interior through most of his career before coaches deciding he grew too big for it and moved him to pivot, a bit like Nico Gonzalez but the change happened at 15 not 19, so there is a learning curve and he shouldn't be rushed tbh.