Here’s how I’d go about ‘replacing’ Busquets — we sign two DM’s: a solid short term ‘stopgap’ (Romeu/Brozovic) and a developmental undertaking (Vermeeren/Varela/Redondo).
It’s the most viable (and economical) way to go about things.

As I keep saying, Integration matters. Both Romeu and Brozovic are highly experienced & consistent, they’re more than adept at doing the job.
Their assuring presence, in turn, greatly improves the integration process for developmental projects. Less pressure, more time. Win-win.

The other options mandate going all out for someone like Florentino, which is the bold move; high risk/high reward. Or, settling for Amrabat, ‘safer’, less bold; someone who does the job without really being a ceiling raiser for the squad.