I suppose it's possible Caleb and Dylan will both make it out of the entire saga alive (and escape to Costa Rica, or wherever Caleb suggested to Dylan they should go), considering their fate isn't Psycho predetermined, but I can't see a scenario where both would believe Norman (post matricide) telling them Norma doesn't want to see them anymore and is only talking through him now, not with Dylan knowing about Norman's instability what he does. Also, my guess is once Norman has lost it that much, he won't be able to stand the idea of Caleb still alive, so if Caleb returns to White Pines, that will definitely be that.