Crazy amount of money for Hernandez, but they had to do it now, because they are amortizing the contract over 8.5 years, and it's going to be paid in 5 installments, also stretching out the hit to FFP.
FIFA is going to close this loophole that the US billionaire figured out in the summer, limiting amortization of player contracts to 5 years. By paying a bit over the odds, in advance of the summer, Hernandez is only going to cost them 14M a year rather than 24M a year, thanks to the much longer amortization period that will be gone by the summer. (Actually, it's going to cost even less than that, because of the fee being broken into installments, so maybe only 8 or 10M a year against their FFP "account".)
They have to sell 5 or 6 guys this summer (mostly high wage guys, too), and will still be looking for a striker (Vlahovic from Inter, replacing Havertz), maybe another athletic midfielder like Onana from Everton or Caicedo from Brighton to pair with Hernandez.
I don't see N'Golo Kante being renewed. He's always hurt and you have to transition to the new guys with the younger legs.
I could still see them add one more center back (Koulibaly will be sold this summer), and are looking at David Raya in goal, probably selling Edou Mendy.
Aubamayang will be gone. Mount might leave this summer, if they sign Felix to a permanent deal.
Ziyech is already gone to PSG (I believe the paperwork issue will be sorted out; there will be enough evidence of timely announcement and filing of the deal).
They might keep Pulisic around as a squad player if the sell Sterling or Mount. He could play on the left wing (alternating with Mudryk) or playing the 10, alternating with Felix / Mount.