I expect to continue seeing what we've seen from Ramsey: he won't be fit for any period of time long enough for us to be able to depend on him
If Tonali can't break into a midfield of whoever remains of Matuidi, Khedira and Rabiot then he's really not that good.
At best, I see us getting someone like Aouar instead of Tonali, but not both.
It all depends on who leaves I think. We've got 6 CMs and I'd group them on likelihood of being kept/sold like this:
To stay: Bentancur, Ramsey, Matuidi (50-50 I'd say)
To go: Khedira, Pjanic, Rabiot
Now, in the most extreme scenario we could offload even 4 CMs. Realistically we'll get rid of two/three: Khedira is a sure bet for me but it'll take some money to rescind his contract. Pjanic could be sold simply because of his age and wages. Also, he doesn't seem like indispensable player anymore, so he's valuable as a bargaining chip. For whom? My guess would be to swap him for Jorginho, less likely for Arthur and Pogba. There were also Paredes rumors...
Rabiot might be offloaded due to his antics and usefulness-to-wages relation. If Everton throws 20m at Tici, I think he'll take it and run. With whom he should be replaced, that he'll worry about later.
So in the end it depends on how many CMs will eventually go. I'd say it's realistic to expect Jorginho + Tonali/Locatelli + Aouar/Pellegrini, if the three above mentioned actually go. Arthur is difficult to guess and Pogba is simply difficult to pull off, with his wages and transfer fee, but who knows. Perhaps OGS decides he likes DC + Rabiot pair and there will be a deal.
The budget will surely be restricted, mostly because of Higuain, who seems to be out of the club already. Hopefully the club settles for a cheaper bench attacker then, the midfield needs rejuvenation and more creativity.