They’re in a tough situation. What you omitted from your dark scenario is that for most Serie A clubs, Champions League is their everything unlike the Premier League teams and maybe 4 or 5 other European clubs at best. So failure to qualify this year would be financially ruinous.
A really big deal could work. Options for someone like Kola, Torreira or Xhaka are unlikely but could help get it over the line. The nice thing about Koulibaly is he’s mature and can be a tutor for Saliba and Holding. We can still wring 4-5 years out of him.