For me Solskjaer started to make some of the right moves last season especially in the transfer market, and while there are still obvious weaknesses at the back the improvement going forward was obvious, massively helped by the huge success of Fernandes.
Any team however is only as good as it's weakest links and United's keeper and backline keep letting them down badly. A bit like Liverpool were before they signed van Dijk and Alisson they need to strengthen these weakest links to make the biggest strides of all.
In effect telling Sheff United they better start looking for another goalkeeper is a major step forward. Solskjaer relatively recently awarded de Gea a lucrative renewal deal and has been big enough to eat some humble pie here. A bit like Guardiola signing Ederson after spending the whole of the previous season defending his own big error, Clownio Bravo, convincing noone not even himself.
This is a massively positive move and I'd expect Henderson to soon grab the jersey. Even if de Gea starts, his first bad game will be his last, and that won't be long in coming, but if the pressure somehow transformed de Gea into reaching his former heights of a few years back then all the better he's won on both counts.
They finished in the top four last season something far more worthwhile than any cups imo and this could take them on a stage nearer the very top. There's still those other obvious defensive weak links to sort out but Olé is gradually grabbing hold of the steering wheel.