They sack OGS and hire someone competent
They will sooner or later hire someone competent, but it is just a question if they give him time to do a proper rebuild. I have been critical to all the four latest manager appointments and got it pretty much spot on.
Moyes - No matter who you brought in it would have been difficult. Especially with Ferguson lurking around and having a stand (opposite the bench so it is visible to the new manager everytime they loose a game) named after him. But David Moyes? Football is luckily not that easy.
LVG - My Manc friends cheered the Netherlands trashing of Spain in the world cup the summer he finished the Netherlands job and started the United one as a new PL title. But I have seen LVG in work. He just bore people to death, and he dictate everything. There will be no freedome for any player to roam. He managed Barcelona a year Iived in Spain and this guy is truly a micromanaging character. However it didn't help Barca at all and for every post match press conference the fluent Spanish speaking Dutchman brought a translator so all questions were translated and hence the temperature just died out. One game they were 3-0 down 20 minutes from time and he made a substitution. When cameras zoomed into the touchline his asstance went through a whole book of instructions to the poor guy coming on. If he was supposed to be capable to absorbe all that info and then turn around the 3-0 in 20 minutes maybe he should have started the match?
Mourinho - This time my Manc friends was sceptical, but they were willing to take him as it meant they were secured a League title. And after a very bright start they actually tought he had changed from sosiopath to a likeable humble guy. Not so much it paaned out and after his first season they started to loose interest in footie.
Solskjær - What a crazy choice. People over here just laughed, but with that bright start they actually started to believe... Talk turned around and people praised him as if he could walk on water.... Again not so much. People hardly remembered what he did at Cardiff, and those who did anyway blamed that on Cardif...
So who next? Allegri as a strong character but defensive approach? Pochettino drained after 5 hard working years at Spurs? Wenger, who while he is a capable character he would still be ripped apart for every defensively mistake they do? Simeone who will need to adjust and settle in a country he doesn't know the language? Tuchel? Jardim? Will they go for another unproven one and risk the same crash and burn proscess as they are experiencing now? Will they go for a proven Italian character who likes it better in Italy anyway? Whatever their next move is it is going to be a huge risk and take time. They will be a force to reckon ones again, but there are no guarantess that the next appointment is the one that sorts things out. However, it is hard to say what a successrate is at this stage, is it to challenge for top 4? That should be achievable for probably all mentioned above with those resources at hand.