I think ex players who possess the right qualities for management, always have a good chance if they have the right temperament, the right resources and have been coached by the best.
Nobody was tipping Pochettino, Guardiola, Zidane, Rijkaard to be great managers but it happened as they were given the right coaching and ingredients for it to happen.
Even if Ole fails, he will still leave a side far closer to what Utd is about for the next guy, bringing hopefully some kids ready to explode such as Sancho, Rice, Issa Diop, Tielemans etc.... And that can only be a good thing for Pochettino in summer 2020 if Ole has failed by then.