Even if the sale happens tomorrow, there's no guarantee large amounts of money will be spent or that it will be spent wisely. Ratcliffe isn't exactly running a model organization over at Nice and PSG is the cautionary tale of what happens when you spend unlimited funds poorly. They can still win a league title because it's France but they should be much more successful in the CL than they are. Point is, there is always reason to be pessimistic. But let's roll the dice and see what happens.
We need to move Maguire out but I don't think we need to spend 80 million to replace him. Or rather I don't think you want to replace him with a finished product. Ideally, you replace him with a youngish CB who isn't going to expect to play every week but is capable of stepping in when Varane inevitably gets injured. I know little about him but Min Jae Kim fits the profile and apparently there's a small window of opportunity to get him for a reasonable price (45 million EUR) this summer. Point is I'd roll into next season with Martinez, Varane, Lindelof, and someone like him and feel good about it.
We desperately need to upgrade De Gea. I think that will be the first big signal of whether this transfer window will be good or not. His contract runs out in 27 days and I honestly have no idea how this will turn out. The fact that he hasn't re-signed is telling in spite of all of ETH's in season proclamations about wanting him back for next season. He either really wants him but only at a lower wage to give him options elsewhere, really wants him but wants to bring in competition, or doesn't really want him but didn't want to cause a big distraction mid-season because it wasn't like he had a realistic better option. All of these seem equally plausible.
But the two areas which need the most help are midfield and forward. At forward we have virtually nothing. In midfield, we are desperately short of the profile that ETH likely values most. Honestly, we could do with 2 forwards and 2 midfielders (at least). I'm beginning to come around a bit on Mount but still think Chelsea isn't letting him go unless they get stupid money.
If you told me would get 2 high quality midfielders, 2 high quality forwards, move Maguire and upgrade De Gea, and nothing else, I would pass out from ecstasy. I doubt we'll get all of that but that would be a fantastic improvement even if it left the outside forward and right back positions untouched.